The only U.S.-market diesel passenger car meets new regulations for clean emissions and offers strong performance at a "bargain" price
It's no secret that most Americans are less than fond of diesels. Past U.S.-market diesels have been clattery, smoky and painfully slow compared to gas-powered counterparts, and U.S. diesel fuel has been sticky, stinky, harder to find, and little (if any) cheaper than gasoline. Unless they've traveled to Europe lately, where quicker, quieter and nearly smokeless modern diesels have become more popular than gas burners due to their higher fuel economy and lower fuel taxes, they've had little reason to change that opinion. Until now.
Two important things are about to start changing it: First, 80 percent of U.S. diesel fuel by law will contain less than 15 parts per million of sulfur (vs. the previous 500 ppm), by this Oct. 15. Second, Mercedes-Benz will take advantage of this new ultra-low-sulfur fuel beginning the very next day by marketing a version of its 2007 mid-range 320 sedan powered by an all-new 208-hp 3.0-liter turbodiesel V-6 (replacing the previous in-line six) with "BLUETEC" exhaust-cleansing technology. M-B BLUETEC diesels will then spread to other markets and models, including a diesel Jeep Grand Cherokee and other Chrysler products.
Mercedes says this new E320 BLUETEC provides "outstanding driving dynamics, unprecedented efficiency and impressive environmental
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compatibility." With its prodigious 388 lb-ft of torque, it offers owners the rare combination of V-8-like performance (zero to 60 mph in 6.6 seconds), four-cylinder economy and up to 700 miles of range - better on all counts than a similar-size gas V-6 - while showing little overt evidence of dieselness.
BLUETEC is a concept that Mercedes says will clean diesel emissions enough to meet more advanced diesel regulations taking effect for the 2007 model year. Including the Bluetec's catalytic converters, the system also uses particulate filters and a new system that treats nitrogen oxide emissions enough to meet the more stringent standards.
All this gets the '07 E320 BLUETEC into EPA's "BIN 8" emissions category, clean enough for 45 states in 2007 but not for California and those four pesky northeastern states that insist on emulating California's standards. The next step needed to satisfy their tougher "BIN 5"requirement (which will be the 50-state federal standard in 2009) will be an additional module involving injection of liquid urea, called AdBlue, into the process, reducing nitrogen oxide emissions another 80 percent. The AdBlue system will require regular fill-ups of fluid, likely to be done at the same time the car has an oil change.
The EPA is working with automakers to determine how to ensure that diesel owners do refill their urea tanks as needed - perhaps by mandating greatly reduced performance by the engine, or even preventing the engine from starting when the urea tank is empty. To our knowledge, M-B will be the only OEM offering (45-state) passenger car diesel engines in the U.S. until this issue is resolved.
The only diesel
Other than offering America's best (and, for a while, only) diesel passenger-car engine, the E-Class is modestly upgraded for 2007. Most significantly, it debuts M-B's first extensive use of lightweight aluminum body panels and chassis components in volume production, including the hood, front fenders, deck lid, front and rear subframes, and more.
The frontal look is mildly restyled, more aggressive, and more aerodynamic, while the interior gets a new steering wheel and shift lever and a nicely revised layout for the automatic climate control. The drag coefficient improves to 0.27 vs. the previous 0.29. New standard equipment includes a glass sunroof, a Harman/Kardon Logic 7 premium audio system with a six-disc CD changer and (for the wagon) a power liftgate. The rain-sensing wipers follow separate patterns to maximize the area cleared, their blades are hot-air heated when parked, and the washer fluid is electrically heated. Optional bi-xenon headlights rotate slightly with the steering to better illuminate curves.
The E320 BLUETEC drives through M-B's seven-speed adaptive transmission, which allows manual gear selection by moving the lever slightly left to downshift or right to upshift (there's no separate gate). We questioned the usefulness of this normally much-appreciated feature, however, given the diesel's relatively narrow torque band. To protect the engine from over-revving, it won't downshift above about 2000 rpm, and it won't hold a gear while accelerating. Instead, it merrily upshifts whenever it pleases. Our test car's transmission also was reluctant to downshift from second to first to take advantage of that strong diesel torque to shoot a gap in traffic, a shortcoming worsened by the turbo's substantial low-speed lag.
We found the chassis dynamics well up to M-B standards and slightly improved over previous E-Class sedans, partly due to quicker response (2.8 turns lock-to-lock vs. the previous 3.3) from the speed-sensitive power rack and pinion. The standard ten-way power front seats were supportive and comfortable throughout a long day's drive. Standard safety features include M-B's "PRE-SAFE" system - which senses an impending crash, tightens the belts, repositions the front passenger seat to a more favorable position, and even closes the sunroof - plus eight airbags, active front head restraints, rollover protection, and "Tele Aid," which locates the car via GPS and calls emergency response in case of a severe collision.
The biggest surprise of all, given this sophisticated new diesel V-6's inherent higher cost and all its expensive emissions-cleansing hardware, was the E320 BLUETEC's modest $1000 premium over a comparably equipped gas-powered E-Class sedan. Its starting price of $52,325 is hardly trivial, but it's a flat-out bargain for what it is. We're guessing it's substantially subsidized to make it more attractive until its U.S.-market reputation is assured.
2007 Mercedes-Benz E320 BLUETEC
Base price: $52,325
Engine: 3.0-liter DOHC diesel V-6, 208 hp/388 lb-ft
Transmission: Seven-speed automatic, rear-wheel drive
Length x width x height: 191.0 x 71.7 x 58.4 in
Wheelbase: 112.4 in
Curb weight: 3860 lb
Fuel economy (EPA city/hwy): 27/37 mpg
Major standard features: Dual-zone automatic climate control; glass sunroof; Harman/Kardon Logic 7 premium audio with six-disc CD changer; power tailgate (wagon); heated windshield wipers and washer fluid; multi-function display; ten-way power front seats
Safety features: M-B Pre-Safe system; dual front, front and rear side, and curtain airbags; anti-lock braking, stability control and tire pressure monitors; active front head restraints; daytime running lights (DRLs); Tele Aid emergency response system
Warranty: Four years/50,000 miles