Why settle for a simple solution when a complicated one will do?

I have written often about the auto industry's quest for alternative fuels; it is a fascinating and fast-moving topic. And yet, with every new breakthrough, I have to wonder why American motorists are so absorbed with Holy Grail technologies like fuel cells that are still years away, yet so completely oblivious to the open secret that common diesel is an efficient technology already amongst us.

The Euros know this already. Some 40 percent of all commuter vehicles are diesel-powered in Europe, where the equivalent of $5-per-gallon fuel puts a premium on 30- to 50-mpg performance. In North America, by contrast, diesel power is shunned as dirty, smelly, sooty, noisy and suitable only for truckers and farmers.

My conscience forces me to admit that I take all of these slanders personally. I own a diesel sedan - a 1976 Mercedes-Benz 300D, purchased new - and I simply don't understand how the typical, well informed auto enthusiast can be so misinformed about both the sophistication and the performance of modern diesel engines.

New Age diesel

Mercedes doesn't understand either, although the company is giving us North Americans yet another chance to learn at our own pace. Despite withdrawing its diesel E-Class from the U.S. in 1999, Mercedes returns in April with the 2005 E320 CDI, whose hyper-modern powertrain will delight techies, excite performance buffs, and still manage well over 30 miles per gallon.

Otherwise indistinguishable from the rest of Mercedes" E-Class lineup, the CDI diesel actually transforms the experience of driving a luxury sedan. The key to it all is the 3.2-liter in-line six underhood. Its twin-cam design incorporates two fascinating features: common-rail direct injection (CDI) and variable nozzle turbine (VNT) turbocharging. Thanks to CDI, this engine is arguably the most precisely efficient powerplant on U.S. roads today. It combines fuel-system pressures approaching 23,000 pounds per square inch with electromagnetic fuel injectors built to microscopic tolerances. The result is precise yet stingy metering of fuel in nearly molecular increments. Thereupon, the computerized VNT turbo adjusts its vane angles instantaneously to cram exactly the right amount of air into the cylinders for maximum combustion energy.

If you don't believe what you cannot see or hear, then consider this: You won't find the first sooty smudge on a white handkerchief held over the tailpipe. Emissions meet EU requirements, which are as much as 58 percent more stringent than our own EPA's. You'll scarcely hear the CDI's 44-dB idle noise or its 72-dB full-throttle acceleration. By comparison, Mercedes" 3.2-liter gasoline V-6 idles at 42 dB and accelerates, full-throttle, at 76 dB. (An average conversation, by the way, registers 60 dB.) Best of all, the CDI sprints from zero to 60 in 6.8 seconds, which is 0.3 seconds faster than its gas V-6 sibling.

All this from a mere 201 horsepower, you might ask? Yes, indeed, because paired with that admittedly uninspiring number is a rating of 369 ft-lb of torque. Torque, or pulling power, is what "feels" sporty in stop-and-go driving, and 369 ft-lb is stratospheric, particularly since it peaks quickly at 1800 rpm.

This is what makes the CDI so fun to drive. It leaps from stops like a rifle shot. When overtaking slower vehicles on the freeway, the CDI powertrain accelerates like an electric motor, rarely pausing to downshift into a lower gear. The Euros drive the wheels off this 3835-lb car precisely because all that torque creates a sensation of sporting about in something hundreds of pounds lighter. I drove the wheels off the CDI at its media debut in San Antonio, complete with back-road strafes and triple-digit highway sprints. For my trouble, I was rewarded with 31.5 mpg.

Benchmark for luxury

The CDI diesel is an ideal choice for Mercedes" E-Class sedan. This is one of the world's benchmark vehicles in the luxury car class, and the unique personality of this new diesel adds a new level of refinement. The cabin is a wraparound envelope of leather and burl, and there is simply no indication of a diesel underhood until the right foot tips the accelerator. How ironical, then, that with Mercedes" near-total banishment of "diesel clatter," the E320 CDI should suffer so much road noise through the wheels and tires. On the pebbly, rough, "sealcoat" surfaces of Texas hill country highways, the Mercedes" cabin was awash in white noise.

I have, moreover, complaints with two design elements that are exclusive to Mercedes interiors. The one is the company's curious and persistent decision to place its cruise-control stalk side-by-side the turn-signal/wiper stalk. Countless are the times my left fingers mistake one for the other while my eyes are on the road. Can I possibly be the only Mercedes driver with such an inexact sense of touch?

My other complaint concerns Mercedes" glacial progress in improving its COMAND telematics. This over-busy system for integrating music, navigation, and telephone is a proliferation of buttons and screens. Moreover, the buttons on the dash are labeled with text on the screens, and these labels change according to mode. I almost despaired of retrieving a favorite CD: Not only was the "eject" button nowhere near the CD slot, it wasn't even associated with the "audio mode" screen.

Gadget gripes aside, I can't imagine Mercedes having any difficulty in selling all 3000 CDI diesels it's importing to the U.S. for 2005. Price, though unannounced at press time, will compete with the E320 gas V-6 model; and that means a base near $48,000. Already there are plans for all-wheel-drive "4Matic" versions of the CDI, possibly by year's end. As for my opinion of diesel-powered passenger cars in general, however, even yesterday isn't soon enough. What's not to get about having your performance, your luxury, and your mileage too?

2005 Mercedes-Benz E320 CDI
Engine: Turbocharged 3.2-liter DOHC 24-valve in-line six, 201 hp/369 ft-lb
Transmission: Five-speed automatic with TouchShift control, rear-wheel drive
Length x width x height: 189.7 x 71.3 x 57.2 in
Wheelbase: 112.4 in
Curb weight: 3835 lb
Fuel economy (EPA city/hwy): 27/37 mpg
Safety equipment: Front, front/rear side and curtain airbags, anti-lock brakes, stability control system, electronic brake-force distribution
Major standard equipment: Dual-zone automatic climate control, 16-inch wheels, AM/FM/CD, TeleAid, rain-sensing wipers, COMAND, fog lamps
Warranty: Four years/50,000 miles

 

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