TAKE it from someone who spent a childhood in the backseat of diesel-powered cars: they stunk.
It wasn’t just the noxious spew from the tailpipe or the kerosene odor you endured while filling up next to towering 18-wheelers. The engines clattered and shook, or they refused to start at all on frigid Michigan mornings. They even caused cancer: several studies found the sooty exhaust to be a carcinogen, and it was linked to asthma, heart attacks and premature deaths.
My only fond diesel memory was how my penny-pinching father coaxed 300,000 miles from his oil-burning Mercedes-Benz cars and International Harvester trucks, which invariably outlived their rusting bodies.
So when I say the new Mercedes E320 Bluetec is one impressive machine, it is not a judgment colored by nostalgia. Swift, quiet and odor-free, this is definitely not my daddy’s diesel. Indeed, the Bluetec probably strikes the best combination of space, performance and efficiency on the road.
You associate 38 miles a gallon with squirrel-driven subcompacts, not a powerful midsize luxury sedan. But that is the mileage the Mercedes test car delivered in 250 miles of highway cruising. The Bluetec also posted a thrifty 28 m.p.g. in the city. Both numbers exceeded the car’s federal rating of 37 on the highway, 27 in town.
With its sizable 21.1-gallon tank, travel range becomes a selling point: the Bluetec can cover a remarkable 700-plus highway miles on a tank, or enough to travel from New York to Indianapolis (or from Los Angeles to Salt Lake City). Such all-day range saves time as well as money. Based on the 32 m.p.g. that my test car returned over all, an owner who drives 15,000 miles a year will pull over for fuel just twice a month.
If there is a downside, at least it is temporary. While the E320 Bluetec is currently the world’s cleanest diesel — and like all diesels, it produces 20 to 40 percent less greenhouse gases than gasoline engines — its levels of smog-forming nitrogen oxides still preclude its sale in California and four Northeast states, including New York, that follow California’s emissions rules.
That is likely to change in 2008, when a final piece of technology should let Mercedes diesels meet even stricter 50-state standards that take effect in 2009. Once federal regulators sign off, several Mercedes models will carry a small tank of urea, a fluid that releases ammonia to convert smoggy nitrogen oxides into nitrogen and water. The tank must be replenished every 15,000 miles or so, in a process akin to an oil change.
But for now, the E320 is the only 2007-model diesel automobile in the United States, to be joined next year by a Jeep Grand Cherokee and three other Mercedes models. Honda recently showed its own diesel that will, it says, meet the 50-state standards within three years with no need for urea. By 2009, General Motors plans to sell a urea-free 50-state diesel V-8 in a pickup truck. Diesels from three other German carmakers — Audi, BMW and Volkswagen — are expected to use similar technology. That outpouring wouldn’t be possible without a momentous shift that starts today: a federally mandated rollout of diesel fuel from which 97 percent of the polluting sulfur has been removed. Once diesel’s sworn enemies, environmental and regulatory groups are hailing the move, which Stephen L. Johnson, administrator of the Environmental Protection Agency, called “the single greatest achievement in clean fuel since the removal of lead from gasoline” in the 1970’s.
The E.P.A. estimates that the greener fuel will ultimately save $150 billion a year in health and welfare costs and prevent 20,000 premature deaths annually.
As with the adoption of unleaded gas, the cleaner fuel opens the door to pollution-fighting gear that should make diesels as clean as the top gas models. In contrast to ethanol, available in far fewer than 1 percent of the nation’s 170,000 gas stations, diesel is pumped at 40 percent of them.
The diesel E-Class is largely indistinguishable from gas versions: same styling, same luxurious interior, same cavernous trunk. All ’07 E-Classes have a mildly revamped exterior and interior and an excellent seven-speed automatic transmission.
Now, 208 horsepower may not sound that forceful. But take a look at the 400 pound-feet of torque, which exceeds that of the 500-horsepower BMW M5 sedan. Commanding torque — the thrust you feel when racing away from a stoplight — is the secret weapon of diesel engines. Abetted by a turbocharger in the E320 Bluetec, this results in swift 0-to-60 acceleration of 6.6 seconds.
That is neck and neck with the car’s gas-powered V-6 twin, the E350 sedan. Yet in my testing, the Bluetec sipped far less fuel, beating the E350 by about 40 percent: 32 m.p.g. over all, versus 23 for the E350.
As for other differences, the E320 skews toward luxury and a comfortable ride, forgoing the E350 Sport’s lower stance, sportier bodywork and firmer suspension. The 16-inch wheels and tires (designed to optimize economy) look a bit scrawny and don’t grip as well as the 18-inchers on the E350 Sport.
The engine is slightly louder at idle, though not obtrusive. Precise common-rail fuel injection raises power while cutting emissions and noise; the cleaner fuel burns more quietly and completely.
Under acceleration, the diesel’s deep drone is less pleasing, but at a steady cruise, the car is so smooth and quiet that even a sharp-eared engineer might not realize there is a diesel engine is under the hood.
For luxury buyers who have suddenly awakened to the imperatives of economy and conservation, this is a no-brainer bargain. With a base price of $52,325, Mercedes is charging just $1,000 extra for the frugal engine and Bluetec emissions system, compared with the gasoline V-6. Contrast that with the big premiums for luxury hybrids: the Lexus GS 450h costs $8,000 more than the gasoline V-6 version, yet its overall E.P.A. rating is just 1 m.p.g. higher, at 25.
In the real world, this means that in about two years the Mercedes — even with diesel now going for only pennies less, on average, than premium gas — will save an owner enough in fuel bills to offset its added cost.
In contrast, the owner of a Lexus GS 450h might as well be Rip Van Winkle: he will have to drive the car more than 130 years to get back the premium.
INSIDE TRACK: Fill it and forget it.
http://select.nytimes.com/preview/2006/10/15/automobiles/1154649821043.html
