34 IEEE Spectrum | April 2006 | NA www.spectrum.ieee.org
Hybrids square off against diesels for the economy laurels
BY JOHN VOELCKER
L ight, ethereal, and nimble, the 2006 Subaru R2 Type S is the face of automotivetechnology that wears the halo. Drive me, it whispers, and youll get incrediblefuel efficiency. Youll accelerate smartly while burning less imported fuel.Over there, wearing the horns, is the huge
and brutal Bugatti Veyron 16.4, which goes from0 to 100 kilometers per hour (62 miles per hour)in 2.5 seconds and burns as much as 26.1 litersof gasoline to go 100 km. Drive me, it growls,and you can humble every other vehicle on theroad. All you need is US $1.2 million.
Two road machines, for the soul and for thebody, for Dr. Jekyll and for Mr. Hyde. Every
other car today falls somewhere in between, atradeoff between gas-guzzling darkness andenvironmental light. The dichotomy, sharp fora long time in much of Europe and Asia, becamemore so this past year in the United States, afterHurricane Katrina kicked gasoline prices brieflyto $3 per gallon.
Nowadays, two technologies are battling forthe halo. In one corner stand Japanese and U.S.
definition radio into its flagship 7 Series.Several manufacturers have integrated livefeeds of traffic news into their navigation sys-tems. The Mazda Sassou concept car forgoesan ignition key for firmware burned into a USBdevice. Fiat SpA announced that all its mod-els will soon have USB ports to handle, well,who knows? A video game? Camera? Printer?The mind boggles.
Last years single highest-tech car didnthave an iPod or an HD radio. In fact, it didnteven have a driver. In October, a bright blueVolkswagen Touareg sport-utility, nicknamedStanley, navigated itself through a treacher-ous, 211-km (131-mile) course in CaliforniasMojave Desert in 6 hours, 54 minutes. By doingso, it captured for its creators a $2 million prizeoffered by the U.S. Defense Advanced ResearchProjects Agency, or DARPA, to promote thedesign of autonomous vehicles. Stanford Uni-versity engineering students, helped by Volks-wagen of Americas Electronics ResearchLaboratory in Palo Alto, Calif., included a cam-era and laser sensors in Stanley that fed datato six Pentium computers, which handled theengine and the steering. On the side of thevehicle, the cheeky students actually rewroteVolkswagens slogan, from Drivers Wantedto Drivers Not Needed.
Dont look for self-driving cars in showroomsanytime soon. But do notice the small but sig-nificant milestones in that direction, such as the2007 Lexus LS460 sedan, which will be able topark itself with minimal help from the personsitting in the drivers seat. Unlike the humandriver, it cant be distracted by the iPod.
2006 SUBARU R2 TYPE S
BUGATTI VEYRON 16.4
companies, which have invested billions of dol-lars in hybrid-electric technology. In the othercorner are European makers, with decades ofexperience in light-duty diesel engines.
Todays hybrids cost so much to build thattheir fuel savings may not cover the highersticker prices. They are most fuel-efficient inurban, stop-and-go traffic, and least economicalat freeway speeds or under hard acceleration.
Diesels, on the other hand, tend to be dirty,and some of the air pollution standards theyhave to meet, such as those in California, arethe worlds strictest. Yet the will to make a cleandiesel is there, because the engines are so fuel-thrifty. When DaimlerChrysler AG drove adiesel version of its Mercedes-Benz ML sport-utility vehicle and the similar-sized LexusRX400h hybrid from New York City to SanFrancisco this past August, the diesel achieved9.1 L/100 km (26 mpg), while the hybrid got 10.2 L/100 km (23 mpg). Still, diesels, too, comeat a price: U.S. consumers, unlike Europeans, payas much or more for diesel fuel as for gasoline.
Technology is blooming not just under thehood but in the passenger compartment as well.Carmakers are falling all over themselves toaccommodate the ubiquitous Apple iPod intheir stereo systems. BMW is building high-
HELL ON WHEELS: At top speed, the Bugatti Veyron 16.4runs through a full tank of gas in 12 minutes.
LITTLE ANGEL: The Subaru R2 Type S packs a lot of tech,including a supercharger and an intercooler, into a tiny space.
36 IEEE Spectrum | April 2006 | NA www.spectrum.ieee.org
Building on the theme that "small is big,"Ford Motor Co.s highest-tech conceptat Januarys influential Detroit AutoShow was a subcompact sports car. Itwas a tad unusual for a company thatearns much of its North American profitfrom midsize, large, and very largetrucks and sport-utilities.
The Reflex marries a small turbo-diesel, from Fords European Fiesta, to arefined version of the hybrid-electricdrive system used in its Escape Hybridsport-utility.
The basic obstacle to using a conven-tional diesel engine in a hybrid-electricdrivetrain is the fact that both the dieseland the electric motor typically have lotsof torque at low revolutions per minute(around 1500 to 3000). Generally, youwant a fossil-fuel engine that deliverspeak torque at relatively high rpms, sothat when you combine it with the elec-
tric motor you get a curve of overalltorque versus rpms that is fairly flat.Fords 1.4-liter turbocharged dieselengine fills the bill. It generates 41 kilo-watts (55 horsepower) at 6000 rpm and175 newton-meters (129 pound-feet) oftorque at 4000 rpm.
According to Tom Watson, Fordshybrid systems propulsion manager, thelittle turbo diesel suits the parallel electricpower system well. You might as well havea substantial electric motor, he points out,because a diesels high compressionratio18:1 or moredemands a prettybeefy starter motor anyway. And bysmoothing out the load on the dieselengine, the electric-drive system helpsmightily in minimizing emissions of nitro-gen oxides and particulates.
Both the engine and an electric motorof about 30 kW drive the front wheelsthrough a six-speed transmission with
electronic manual shifting. Like the LexusRX400h luxury sport-utility hybrid, theReflex uses an additional electric motor(of 15 kW) to drive the rear wheels andprovide all-wheel drive. Ford quotes fueleconomy of 5.9 to 3.6 L/100 km (40 to65 mpg) but stresses that it is accompa-nied by sporty performance: accelerationfrom 0 to 60 mph (0 to almost 100 km/h)in less than 7 seconds.
Photovoltaic solar panels on the roofand in the lights help too, because eventhough they deliver "watts, not kilowatts,"as Watson says, they can lighten the loadon the high-voltage batteries. Also, thepanels power a small fan that vents heatfrom the car when it is parked.
If public response to a sporty high-mileage hybrid coupe is positive, Watsonsays, perhaps "the stigma of diesels inNorth America can be overcome by thehybrids image."
A diesel hybrid thats both sporty and green
WINGING IT: Ford's innovation-packed Reflex sports carconcept has back-hingedswing-wing doors.
TOP 10 TECH CARS
Chryslers 300C caught on fast after its U.S. introduction inthe 2004 model year. Its a powerful, stylish four-door sedanwith a V8 engine driving the rear wheelsa genre that U.S.makers had ignored for 10 years while focusing on sport-utilitiesand light trucks. To improve fuel economy, an automaticcontrol system shuts the valves to four of the eight cylinderswhen the load is light, giving it a rating of 13.1 and 9.0 L/100 km(18 and 26 mpg) in the U.S. Environmental Protection Agencyscity and highway driving simulations.
The really new technology this year comes up front, in the head-lights. Called SmartBeam by developer Gentex Corp., of Zeeland,Mich., it switches on the high beams when needed, something U.S.drivers do only about 25 percent of the time. Its a problem that aU.S. Department of Transportation study identified back in the1960s. SmartBeam uses forward-facing CMOS image sensors, effec-tively a camera on a chip, built into the interior rearview mirror.The technology keeps the brights switched on until it detects eitherthe headlamps of oncoming vehicles or the taillights of vehiclesahead, then switches to the low beams. To avoid distractingapproaching drivers, the system fades the high beams on and off.
Interestingly, the first attempt at such control was made halfa century ago, when diodes were big and fragile and programmingwas what you heard on the radio. The General Motors Autronic sys-tem (1952 to 1958) switched the high beams according to the lightthat reached a dashboard-mounted direct-current phototubean anode and a light-sensitive cathode enclosed in a glass tube. This
photocell increased currentproportionally to the
light that entered it.
The job was not donewell, but it is amazing that
it was done at all.Chrysler calls this car the Heritage Edition
to commemorate the 50th year of its 300 series,famous particularly for the 1957 Chrysler 300C, renowned for its per-formance. Limited production of the US $36 000 Heritage Edition is sched-uled to begin next month. The SmartBeam system was launched last yearon luxury vehicles from General Motors Corp.s Cadillac and Chryslers Jeep;it also will be fitted to BMWs 5-, 6-, and 7-Series models in Europe.
The most politeand effectiveheadlights on U.S. roads
Youve got mail. Its fromyour car.The latest Chevrolet Tahoe sport-utility and itsGMC Yukon twin are hardly examples of advancedautomotive design. Their rear axles are live, ratherthan independently suspended as on virtually allEuropean cars. Their V8 engines are refined versionsof a decades-old design. And these sport-utilities arebigger and heavier than almost everything sold forpassenger use in Japan or Europe. Like Japans keicars, theyre designed for a specific use in a singlecountry: hauling up to eight people and their lug-gage, even while towing as much as 3500 kilograms.
Tahoes and Yukons do offer advanced technol-ogy. One good example is their OnStar two-waywireless communications system. GM started theservice in 1995 to connect vehicles to a remoteservice center, doing so automatically during emer-gencies. Its best-known feature alerts the Detroitmonitoring center whenever an airbag deploys,whereupon OnStar calls local emergency serv-ices to check on the vehicle and its occupants.
Now GM has taken that connectivity a stepfurther, to remind owners about maintenance.Starting last August, owners who used any non-emergency OnStar function were reminded ofoutstanding recall noticeswhich they alsoreceive through the mailand were connected todealers to schedule a repair visit. Beginning thispast January, OnStars central computersbegan e-mailing owners to remind them ofupcoming maintenance tasks like oil changesand to confirm that the vehicles safety sys-tems are working properly.
The OnStar system consists of a digital cellulartelephone built into the vehicles audio system, alongwith a six-channel Global Positioning Systemreceiver that continuously pinpoints its location.OnStar monitors dozens of functions with sensorsthat collect data on acceleration, braking, steeringangles, body roll, oil pressure, gasoline level, andmore. It can also detect when a vehicle is beingdriven "too aggressively" by comparing a carsperformance data to its norms. If OnStar deems thecars on-road activities too extreme, it calls the driverto make sure everythings all right.
www.spectrum.ieee.org April 2006 | IEEE Spectrum | NA 37
BRIGHT IDEA: Head-lights on the Chrysler300C can switch auto-matically between thehigh and low beams.
CAR CONNECTIVITY: The OnStarsystem reminds owners ofvehicles like thisYukon about necessary maintenance.
In the United States, diesel engines stillcall up images of roaring 18-wheelers atbestand smoky, unreliable 1980s Olds-mobiles at worst. In Europe, on the otherhand, more than half of all passenger carssold have diesel engines, and some of themare among the best appointed and mostprestigious in their lines. But those dieselscant be brought across the Atlantic,
because the United States puts far morestringent controls on emissions, andbecause the cleaner diesel fuel widelyavailable in Europe hasnt yet reached U.S.pumps. The few diesel vehicles now soldin the United States by Mercedes-Benz,Volkswagen, and Jeep are available in45 states. But of the five states where youcant get them, two are auto-marketwhoppers: California (which has ultrastrictemission standards) and New York (which,like three other Northeastern states, hasadopted the California standards).
To make the grade, Mercedes-Benzdeveloped the Bluetec diesel engine. In
its basic form it scrubs the exhaust inno fewer than three cat-
alytic converters. First,
an oxidizing converter treats hydrocarbonsand carbon monoxide in the exhaust.Second, a new DeNOx storage catalyticconverter adsorbs nitrogen oxides (NOx)on the surface of the many fine grains ofactivated carbon of a filter; later, that storedNOx is flushed out and shunted back intothe combustion process, where it is largelydecomposed. Meanwhile, troublesomeparticulates collect on a filter hot enoughto burn them away, so that nobody everhas to clean the thing. Finally, a thirdcatalytic converter cleans the treatedexhaust further in a process known asselective catalytic reduction.
A more complex form of Bluetecreplaces the DeNOx (stage two) converterwith a system that injects liquid urea intothe exhaust gas, where it releases ammo-nia, allowing the final catalyst to convertNOx into nitrogen and water. The carcomes with a 20-liter tank of urea thatis designed to last for 20 000 kilometers(roughly 12 000 miles)long enough,Mercedes says, to leave the refilling ofthe tank for scheduled maintenance atthe dealership.
The treatment cuts NOx emissions byup to 80 percent over the E 320 CDI, anIEEE Spectrum Top 10 Tech Car last year.
The E 320 Bluetecs 155-kilowatt(208-horsepower) 3.0-L turbocharged V6diesel engine develops 540 newton-meters (398 pound-feet) of torque
Japans tiny kei cars, unknownin the United States and rarely
seen in Europe, were created in re-sponse to laws that give owners reducedtaxes and insurance costs andbest ofall, in Japans crowded cities, anywayfree parking. To qualify, a car must beno more than 3.4 meters long, 2 metershigh, and 1.48 meters wide, and its enginemay displace no more than 0.66 liters,or 660 cubic centimeters, and produce nomore than 47 kilowatts (63 horsepower).
Daihatsu, Honda, Mazda, Mitsubishi,Subaru, and Suzuki sell kei cars, andmany offer high-performance versionsthat pack nearly as much advanced tech-nology per cc as the gargantuan BugattiVeyron 16.4 (see Endnote). The best ofthe bunch is Subarus R2 Type S, newlyrevised for 2006, because it alone blendsall-wheel drive with a continuously varia-ble transmission (CVT).
a teaspoon under the allowed displace-ment. Unlike some of its kei competitors,it has not three cylinders but four, withfour valves per cylinder controlled bydual overhead cams. Alone in the group,it uses a superchargera mechanicalpump driven off the engines crank-shaftto cram air into the enginescylinders. To pack even more in, the Type Sengine has an intercooler, a radiator-like device to cool the air and thusincrease its density.
Because most kei cars provide as muchpower as Japanese law allows, they com-
The cleanest dieselengine in the world
A teeny-weenyscreamingroad machine
38 IEEE Spectrum | April 2006 | NA www.spectrum.ieee.org
Normally, a CVTscontrol logic optimizesengine efficiency by automatically adjust-ing the gearing ratio to engine speed. ButSubaru has included a seven-speed"manumatic" shifter that is operated bytapping "paddles" behind the steeringwheel to shift up or down. It lets the driversimulate controlling the transmissionmanuallyan odd trick with a continu-ously variable transmission. Of course,the intervention by mere mortals willcompromise efficiency and waste fuel,but so what? This little car wasnt de-signed for ultra-economy but for storm-ing Japans congested urban streets.
At 658 cc, the engine comes about
TOP 10 TECH CARS
MERCEDES-BENZ E 320 BLUETEC2007
BLUE MEANS GREEN:Three catalytic convertersscrub this diesel's exhaust.
www.spectrum.ieee.org April 2006 | IEEE Spectrum | NA 39
equivalent to that of a V8but uses just6.7 L to go 100 km (35 mpg), to propel avehicle that weighs about 1750 kilograms(about 3860 pounds).
Bluetecs scrubber depends on exhaustgas that is pretty clean to begin with,thanks to an optimized combustion pro-cess. Electronic controls coordinate theoperation of each cylinders four valves, ahigh-pressure system that injects fuel intothe cylinders at 159 000 kilopascals (about23 000 pounds per square inch), a turbo-charger that crams in air and, finally, a sys-tem that recirculates exhaust gas back intothe engine. Sometimes, the system injectsa little fuel into the exhaust gas before itreaches the particulate filter, setting up anafterburner to keep the filter hot enough.
Bluetec requires the cleaner form ofdiesel fuel that wont be available in theUnited States until the end of this year.It cuts the sulfur content to 15 parts permillion from the previous U.S. limit of500. Sulfur is a main component of par-ticulates, which have recently beenimplicated in respiratory problems com-mon in urban areas.
The simpler (nonurea) version of Blue-tec is slated to go on sale in the UnitedStates in the E 320 this fall, at a price thatremains to be set. Mercedes plans to offera system incorporating urea injection in aversion of its GL large sport-utility laterin the 2007 model year.
pete on torque and acceleration. At3200 revolutions per minute, theType S generates 103 newton-meters (76 pound-feet), close to thecurrent class champions 110 Nm(81 lb-ft). Its 47 kW (63 hp) is pro-duced at 6000 rpm, typical forthe class. It accelerates from 0 to100 km/h (62 mph) in roughly 10seconds and tops out at 160 km/h(99 mph), best among these tinycars. It uses 5.6 L/100 km (42 mpg)on the Japanese emission stan-dard cycle to propel its total weightof 880 kilograms (1940 pounds).Lesser kei cars with hybrid elec-tric drivesans turbos, all-wheeldrive, and the restcan achieve upto 3.1 L/100 km (78 mpg), but theypay the price: some take as longas 16.5 seconds to get from 0 to100 km/h.
From its beginning in 1989, Toyota MotorCorp.s Lexus has offered luxury, per-formance, handling, and reliability, allat a price the European leaders couldntmatch. Today, a five-year-old Lexusgenerally has fewer problems than abrand-new Mercedes or BMW, and it isthe leading U.S. luxury brand. NowToyota is taking it global, expandingLexus sales into Europe and Asia.
This year Lexus took off the gloves,releasing a feature not found on anyGerman or U.S. competitor. The systemparks the car at the touch of a button, withjust a little braking on the drivers part. Itis used during parallel parking or backinginto a garage. Once the driver specifiesthe parking spot on the vehicles naviga-tion system, it processes images fromfront and rear cameras and uses theresults to control both electric powersteering and the "drive-by-wire" elec-tronic throttle. It works so well its spooky.
The similar Intelligent Parking Assistsystem has been an option on Japanese-market Toyota Priuses for two years,priced at US $2000 in Japan and $700in the United Kingdom. That system,however, requires the driver to operatethe accelerator as well as the brakeswhile the car steers. But pioneering thesystem in the United Stateswherenew product features sometimes lurelawyers like fliesspeaks to Toyotasconfidence that its software is bullet-proof. Lexus is withholding the tech-nological details for release at Genevas76th International Auto Show, in March(after press time for this issue).
In case anyone missed the challengeto other luxury-car makers in generaland Mercedes in particular, the Lexus
LS460 will have the worlds first automatictransmission with eight gearsone morethan the record-setting transmission thatMercedes proudly unveiled in 2003.
The cars 4.6-liter V8 engine generates502 newton meters (370 pound-feet) oftorque and 283 kilowatts (380 horse-power)36 percent more power than itspredecessor. Its enough to kick the LSfrom 0 to 60 mph in 5.4 seconds whiledelivering city and highway fuel mile-age estimated at 9.4 and 8.7 L/100 km(25 and 27 mpg). And, oh yes, a hybridversion will be introduced in April.
The cars electronics are an alpha-bet soup of control and assist systems.The Vehicle Dynamics Integrated Man-agement (VDIM) system mines datafrom a variety of systems to anticipateskidding and helps the driver recoverwith electronically controlled brakes;electronic power steering; vehicle sta-bility control; antilock brakes; brakingassist; electronic brake-force distribu-tion; and engine torque, based on inputsfrom dozens of sensorsand the driver,of course.
Other tech firsts include individualDVD players for each of the three pas-
senger spots. The discrete 5.1 surround-sound stereo system developed byMark Levinson features 19 speakers.Real-time traffic updates are inte-grated into the navigation computer.The climate-control system adjustsitself based on measurements of notonly the ambient temperature in var-ious cabin zones but also of the bodyheat emanating from each occupant.
The luxury-to-dollar ratio is goingto take a big leap in autumn, whenthis ber-Lexus rolls out.
A salvo of advanced automotive electronics and much more
BERSEDAN: It knowswhat your bodytemperature is.
40 IEEE Spectrum | April 2006 | NA www.spectrum.ieee.org
Not long ago, the base model of a pop-ular midsize sedan was a grim place tobe. There was a small engine, a bare-bones gearbox, large expanses of vinyl orplain-cloth upholstery, and maybe anAM radio.
Those days are gone. Consider the new,sixth generation of the Volkswagen Passat,sold in the United States as a sports sedanand available throughout Europe withno fewer than eight different enginechoicesthree diesel and five gasoline.
The entry-level Passat for the UnitedStates is a 16-valve 2.0-liter double-overhead-camshaft inline four. It has aturbocharger, which uses hot exhaust gasto drive a pump that compresses air, anintercooler to increase the airs density,and high-pressure fuel injectors to squirtvaporized gasoline into the cylinder. The
result is 149 kilowatts (200 horsepower)at 5100 revolutions per minute and a re-markably flat torque curve of 280 newton-meters (207 pound-feet) from 1800 to 5000rpm, for plenty of pulling power. Thestandard gearbox is a six-speed manual.
Then theres the optional 3.6-L en-gine, Volkswagens characteristic VR6,with two banks of three cylinders eachin a narrow V shape at an angle of just10.6 degrees, making it both light andcompact. It produces 206 kW (280 hp)at 6200 rpm, but its maximum torqueof 360 Nm (265 lb-ft) comes at just2750 rpm. Mated to the VR6 is a six-speedautomatic transmission that also lets thedriver shift manually. VWs 4Motion all-wheel drive is available as well.
Inside, the car has eight air bags asstandard: two in front, four front- and
rear-side curtains, and two front-sidethorax protectors. Two rear-side thoraxprotectors come as an option. Othersafety features include seat-belt preten-sioners, which better restrain occupantsby drawing the belts taut when the carsenses an accident, and antilock brakescoupled with an engine braking system.The power steering not only varies thedegree of assist with speed and other fac-tors but also helps the driver maintain astraight-ahead path by steering intodeflections from side winds and road ir-regularities. And an electronic stabiliza-tion program monitors speed, cornering,braking, inputs from the drive-by-wirethrottle, and other data to compensatefor slipping traction or sliding tires fasterand more precisely than the driver can.
Despite the technology, the Passat islight on its tires, weighing from 1499 to1737 kilograms (3305 to 3829 pounds),depending on options, with a 0-to-60time ranging from 6.2 to 6.9 seconds.
Some attractive features offered in theEuropean Passats arent available in theUnited States. Among them are bixenonheadlamps that swivel as much as 15 de-grees to illuminate the direction in whichthe car is turning, and adaptive cruisecontrol that uses radar sensing to detectslower vehicles ahead and stay a set dis-tance behind them. The same radar alsosenses critical proximity situations andprepares the Passat for an emergency bymoving the brake pads closer to the disksand increasing brake sensitivity to makesudden braking more effective.
Its every drivers nightmare: you changelanes suddenly, glancing in the rearview mir-ror without looking over your shoulderandyou merge directly into a car hidden in oneof your cars blind spots. The U.S. NationalHighway Traffic Safety Administration saysthat "lane change situations" are involvedin 4 to 10 percent of all car crashes.
Three years ago, Volvo set out to createa system that would warn drivers when othervehicles entered their blind spots. The result,the Blind-spot Information System (BLIS),was recently offered as a $770 option onS60 and S80 sedans, V70 wagons, andXC90 sport-utilities sold in European mar-kets. Volvo expects to offer the systemeventually in all its cars.
Electronic visionunblocks the
EYES IN THE BACK OF ITS HEAD: Cameras catch cars in your blind spots.
Even mass-market cars get seriously sophisticated
TOP 10 TECH CARS
www.spectrum.ieee.org April 2006 | IEEE Spectrum | NA 41
Mitsubishis Concept-CT MIEV, styledat Mitsubishi Motors Design Centerin Cypress, Calif., is a window toan intriguing future of partiallyelectric drivetrains. This com-pact four-door hatchback, just3.8 meters (150 inches) long,deploys four electric motors onthe wheels themselves, ratherthan the usual plan, which is touse one or two central motors deliv-ering power to driveshafts. The MitsubishiIn-wheel Motor Electric Vehicle (MIEV)system is mated to a three-cylinder, 1.0-liter gasoline engine located behind therear seat but ahead of the rear axle line,a "rear-midship" layout typically used insports cars for its low center of gravityand marvelously quick steering response.
Notwithstanding the innovativepower train, the Concept-CT doesntactually run. Why? Well, concept carsrange from pure styling mock-ups to fullyengineered vehicles just a hair away fromproduction. The CT is closer to the mock-
up. The key components are all there toshow they fit and can function within thestructure, size, and shape of the vehicleenvisioned. Its an important first steptoward a "real" car, whether it winds uplooking like the CT or not.
The power train used in the CT devel-ops 100 kilowatts (134 horsepower) intotal, half coming from the small gaso-
line engine, the rest froma lithium-ion battery pack. Theengine would drive the rear wheelsthrough a transmission that also cranksa 40-kW (54-hp) generator, whichrecharges the batteries together withpower recovered during braking. Be-cause each of four 20-kW (27-hp) wheelmotors is individually powered by thecars control electronics, the systemoffers all-wheel drive while losing thedifferentials, with their weight andbulkthus making possible a flat floorfor the passenger compartment. Thedesigners also found an ingenious solu-tion to a difficult problem: how do youcool an engine that sits behind the rearpassenger seats? Answer: they put ascoop in the roof to channel air throughthe cars pillars to the engine.
The CTs four electric motors areexperimental units that feature a hollow-
doughnut construction, in which therotor goes outside the stator instead ofinside it, conserving space and reduc-ing weight. Its a crucial feature, becauseputting a more conventional motor inevery wheel can double its "unsprungweight," that is, the mass of the wheel andhub whose movement the suspensionmust smoothly accommodate.
Mitsubishis goal, the company says,is to launch a production model incor-porating MIEV technology and lithium-ion batteries by 2010. As a step in thatdirection, Mitsubishi is road-testing theMIEV power train in a modified LancerEvo rally car, its fastest and best-knownperformance vehicle.
Two camera modules, one for each doormirror, capture images in a low-resolutionblack-and-white CMOS video sensor,behind glass that is heated, to clear awayfog. The camera, trained on the side reararea of the car, processes 25 images persecond in a signal-processing chip,which uses software stored in the cam-eras flash memory. A control processorsupervises I/O, data transfer, and com-munication among the components.
Say a vehicle enters one of your carsblind spots. Standard vision-motiontracking algorithms recognize the in-truder, the camera module sends analarm signal along a bus, and an LEDmounted near the doors mirror starts
to flash. At the same time, a status mes-sage appears on a dashboard screen.
The challenge, says Lex Kerssemakers,Volvos head of product planning, was in fig-uring out how to distinguish cars from back-ground conditions under a variety of light
levels, sun angles, weather conditions,vehicle speeds, traffic scenarios, roadtypes, and architectural surroundings.The system also has to account for speeddifferentials, because a vehicle travelingat precisely the same speed as ones owncan lurk in a blind spot for a while. A par-ticular problem during development,Kerssemakers adds, was posed by theshadows cast by roadside light when thesun is close to the horizon. Early systems
generated many false positiveswarningsof nonexistent hazards. Although that hasbeen corrected, the system deliberately errsslightly on the side of caution, he says.
Volvo emphasizes that the technologyis meant to support proper driving habitsrather than substitute for them. But Kersse-makers concedes that the company engi-neered the system on the assumption thatlazy drivers will in fact rely on the systemalone. Drivers can switch off the system ifthey wish, but it is switched back on everytime the car is started.
After going back to a car without BLIS,Kerssemakers says he missed the systemand it wasnt just me; all our test driversmissed having the light to warn them.
A whole new meaning for hot wheels
42 IEEE Spectrum | April 2006 | NA www.spectrum.ieee.org
The first hybrids were designed to savefuel. More recently, some designs havebegun trading fuel economy for perform-ance. Now Subaru, which usually doesthings differently, offers both qualitiesin one package. It has added a hybrid elec-tric drive to a turbocharged gasoline en-gine, proposing a compact power trainthats as muscular as the companys stan-dard turbo engine but burns 30 percentless fuel. The B5-TPH (Turbo ParallelHybrid) concept vehicle, first shown at the39th Tokyo Motor Show last fall, is a run-ning demonstration of that technology.
It starts with a turbocharged 2.0-literversion of the companys highly regardedhorizontally opposed boxer engine,generating 191 kilowatts (256 horsepower)and 342 newton-meters (252 pound-feet)
of torque. The engine uses the Millercombustion cycle, which leaves theintake valves partially open at the startof the compression stroke. This schemesaves energy by letting the turbochargerdo some of the compression work thatwould otherwise have to be done bythe pistons. However, at lower enginespeeds, at which the turbocharger gen-erates less pressure, the Miller-cycleengine design produces less torque.
To overcome that drawback, Subaruengineers added an electric motor-generator, just 58 millimeters thick,between the engine and the transmission.Electric motors deliver maximum torqueas soon as they start up, so the hybridsystem neatly offsets the characteristicturbo lag that causes the Miller cycles
low-speed sluggishness. Operating as amotor, the motor-generator produces just10 kW (13 hp) at peak power but a full150 Nm (111 ft-lb) of torque.
Subaru is adapting hybrid technologyfor a variety of engines, transmissions,and vehicle configurations. For instance,it has designed the torque converter tomake it possible to fit the electric motorwithin an existing transmission housing.It delivers power through an automatictransmission to Subarus signature all-wheel-drive system, which varies torqueto each wheel according to changes in roadconditions. Because performance, not justfuel economy, is a goal, both the motorand the engine operate all the time. Thescheme allows for an electric motor muchsmaller than what youd have to put in ahybrid that could run off the motor alone.The entire hybrid package adds just100 kilograms (220 pounds) of weight.
JOHN VOELCKER has written about automotive technology, home building, and other topics for 20 years. He coveredsoftware and microprocessor design for IEEE Spectrum from 1985 to 1990. A connoisseur of vintage British automobiles,he has owned five Riley One-Point-Fives, four Morris Minors, three Pontiac GTOs, and a handful of Subarus.
ABOUT THE AUTHOR
TOP 10 TECH CARS
An opposing take on performance hybrids
SUBARU B5-TPHCONCEPT (TURBO PARALLEL HYBRID)
It has the luxury of a Rolls-Royce, theperformance of a Formula One car, andthe drivability of a Honda. Its a com-bination that leaves the Mercedes-Benz SLR McLaren, the Ferrari Enzo,and other wannabes in the dust.The Bugatti Veyron 16.4 is the fastest,
most powerful, most expensive produc-tion car in the history of the automotiveindustry. Its 8.0-liter 16-cylinder enginehas four turbochargers and produces740 kilowatts (1001 metric horsepower,or 987 hp). And you want torque? Howdoes 1250 newton-meters sound? Thecar reaches 100 km/h in 2.5 seconds froma standing start, and 300 km/h (186 mph)in 16.7 seconds. It has a top speedof 408 km/h (254 mph). And eachVeyron costs a flat 1 million, or aboutUS $1.2 million, plus tax.
The structure is made of carbon fiberand aluminum. The brakes are carbonceramic, and the exhaust system is tita-nium. There are 10 radiators to dissipatethe engines heat. To keep the car on theground when its winglike shape devel-ops lift at high speeds, there are frontand rear air diffusers and a massive rearspoiler that deploys electronically togenerate a drag force of 0.6 times theforce of gravity. Ride height varies withspeed from 125 to 66 mm.
To go beyond 375 km/h (233 mph),the driver must stop the car, insert aspecial key, and go through a checklist("Seatbelts, check; oil, check; last will
and testament, check"). At top speed,the Veyron runs through a full tank ofgas in 12 minutes, for a fuel economymeasured in gallons per mile. The U.S.Environmental Protection Agency ratesit at 9 and 18 mpg in normal city andhighway cycles (26.1 and 13.1 L/100 km).Presumably, though, mileage wont bea factor in anyones purchase of thisvehicle, ever. From 400 km/h, the carcan stop in 10 seconds, covering morethan a kilometer while doing so.
In the rarefied world of the supercar,so-called volume production is meas-ured in hundreds, sometimes just dozensof cars. By that standard, the 300 exam-ples of the Veyron 16.4 that BugattiAutomobiles SAS, of Molsheim, France,expects to build50 per yearqualifyit as a volume car.
Bugatti built just 7000 cars between1909 and 1956, from Grand Prix winnersto the legendary Royale ultraluxury car.It seems the greatest of ironies that thestoried French marque was revived byVolkswagen, the German "peoples car"maker. A pet project of former chairmanFerdinand Pich, the development ofthe Veyron took eight years. Industryanalysts dont expect the company torecoup its investment.
But what a glorious piece of engi-neering it is. Volkswagen should be proud.Perhaps even Ettore Bugatti, a man ofimmense flamboyance, ego, and engi-neering genius, would be pleased.
Batteries are recharged both from enginepower and through regenerative braking.
The B5-TPH shows off another hybridfirst: Subarus manganese lithium-ion bat-teries, developed in a joint venture betweenFuji Heavy Industries Ltd. (Subarus par-ent) and NEC Corp., both in Tokyo. With50 percent greater power density than thenickel-metal-hydride batteries used forhybrids today, lithium-ion batteries alsooffer much faster recharges. Subaru andNEC hint, without giving any supportingdetails, that they have solved lithium ionstwo main weak spots: excessive heat and alimited number of recharging cycles.
The B5-TPH itself is a sporty two-seat, all-wheel-drive grand tourer witha clamshell hatch at the rear. It has ele-ments of a coupe, a sporty hatchback, anda sport-utility. As in Subarus World RallyChampionship cars, the compact turboboxer engine lowers the center of gravityfor better handling. Aggressively treadedtires on 480-mm (19-inch) alloy wheelsand 200 mm (8 inches) of ground clear-ance fit out the B5-TPH for light-duty,off-road travel. The TPH power train isscheduled to be released in a version ofSubarus Legacy sedan in Japan in 2007.
HAVING IT BOTH WAYS:Subaru built this hybrid concept for performanceand fuel efficiency.
www.spectrum.ieee.org April 2006 | IEEE Spectrum | NA 43
1000 HORSEPOWER. ANY QUESTIONS?