2007 Mercedes-Benz E320 Bluetec First Drive

Published: 11/28/2006  - by Jason Kavanagh, Senior Road Test Engineer

Mercedes-Benz wants you to wipe its rear end.

The company has so thoroughly cleaned up the exhaust emissions of its latest diesel baby, the 2007 E320 Bluetec, Mercedes says you can hold a white handkerchief over its tailpipe and it will stay white.

Bluetec, DaimlerChrysler's moniker for its advanced diesel exhaust after-treatment system, makes its world debut on the 2007 E320 Bluetec. So it's not just a car; it's the company's way to make the planet less stinky. And it quashes once and for all the outmoded prejudices the American motoring public holds toward diesel engines. Smoke? Gone. Noise? A memory. Sluggish acceleration? How does zero to 60 mph in 6.6 seconds grab you?

Perhaps to contrast with the car's eco-groovy nature, Mercedes chose hedonistic Las Vegas as the location to let us loose in its latest diesel wundercar. Several hundred miles later, we came away with a renewed appreciation for modern diesel engines.

45-state availability
Mercedes is touting the E320 Bluetec as the only diesel-equipped passenger car available as a 2007 model. Stricter EPA emissions standards, known as Bin 8, affect all 2007 models.

To meet Bin 8 standards, the 2007 Bluetec exhaust system consists of three specialized catalysts and a particulate filter that handles nearly every last trace of smoke. NOx, a persistent by-product of diesel combustion, is controlled by a NOx storage catalyst and an SCR catalyst. These four devices scrub the exhaust gases squeaky clean, allowing the Bluetec to be sold Bin 8-compliant.

That turns out to be 45 states. California, Maine, Massachusetts, New York and Vermont leave Bluetec out in the cold for 2007 due to their adoption of even more stringent Bin 5 standards that take effect in the rest of the U.S. in 2009.

Meeting Bin 5's tighter NOx limits requires the injection of a nontoxic solution commonly known as urea — "AdBlue" in Mercedes-speak — into the exhaust stream. A reservoir containing AdBlue will require periodic refilling, which Mercedes reps say will be performed during the car's normal maintenance. Equipped with AdBlue injection, 50-state-legal Bluetec versions of the E-Class — as well as R-, ML- and GL-Classes — will be available as 2009 models.

In the U.S., the trigger for these high-tech diesels is Ultra Low-Sulfur Diesel (ULSD), which is much more catalyst-friendly than non-ULSD fuel. Bluetecs require ULSD, but that won't be much of a problem. ULSD is already widespread in Europe, and the EPA mandated that it be available in 80 percent of U.S. retail outlets by October 15 of this year. Bluetecs started trickling into dealer lots immediately thereafter.

Diesel dichotomy
Replacing the inline 3.2-liter diesel in the outgoing E320 CDI, the E320 Bluetec employs an aluminum-block DOHC 3.0-liter diesel V6. It's also the same basic engine used in the 2007 GL320 CDI and ML320 CDI. This mill is already available in non-U.S. markets in 13 different Mercedes and Chrysler models, including the 300C and Jeep Grand Cherokee and Commander.

Due to packaging considerations, this engine has an unusual 72-degree "V" angle, so a counterrotating balance shaft is employed to smooth out the power delivery. This is one refined, smooth engine, and most people wouldn't even realize it was a diesel if they weren't told.

Generating 208 horsepower at 3,800 rpm, this diesel gives up 60 hp to the gasoline-powered E350, but that only tells part of the story. Remember, this is a diesel, so it's got heaps of torque. Oh, Lordy, the torque. Thanks to an advanced fuel system and a Garrett GT20V variable-geometry turbocharger, the Bluetec belts out 388 pound-feet of torque from 1,600-2,400 rpm. That's a whopping 130 lb-ft more than the E350, and it makes its presence known when you plant your right foot.

From a standstill, there's only a brief soft spot in the power delivery before the turbo generates meaningful boost, followed by that beefy slab of torque that hauls the Bluetec forward with authority. Mercedes says it's only 0.1 second off the E350's sprint to 60 mph. Once underway, the always smooth corporate seven-speed auto does a fine job of keeping the Bluetec in the meaty part of its powerband. To account for the diesel's inherently lower-revving nature — redline is 4,600 rpm — engineers fitted the taller 2.65 final drive found in the E550 and E63 AMG.

With their gentler combustion characteristics, gasoline engines are typically quieter in operation than diesels. However, the Bluetec is so completely free of diesel clatter and turbo whistle that the only way to tell it doesn't burn gasoline is to note the glacial movement of the fuel gauge.

Easy on the Gatorade
The Bluetec carries a preliminary EPA rating of 26/37 city/hwy mpg, which beats out the E350's 19/26 by a huge margin and even out-economizes hybrids like the Lexus GS 450h. Base price for the Bluetec is $52,325 with destination, which is only $1,000 more than a similarly equipped E350. Factor in the Bluetec's fuel savings and this premium will be offset in about two and a half years at today's (low) fuel prices. Not bad, and when fuel prices climb, the investment pays off sooner. Sorry, wagon lovers — the 2007 E320 Bluetec will only be available in sedan guise, and 4Matic all-wheel drive will not be offered.

The comparison of the gasoline E350 to the diesel Bluetec draws similar parallels among hybrids, but with a startlingly different outcome. For example, the $55,615 hybrid Lexus GS 450h is rated at 25/28 city/hwy mpg. It shares its V6 engine with the $44,865 GS 350, rated at 21/29 mpg. Adjusted for differences in standard equipment, the hybrid commands a premium of $8,565 over the GS 350. But since the hybrid only saves $150 per year in fuel costs, it will take 57 years to recoup the purchase price difference. Use real-world fuel economy numbers, and a solely economic argument for opting for the hybrid gets even feebler.

This real-world value is part of the reason for Mercedes' big diesel push, although global markets also play into the equation. With penetration exceeding 60 percent in several countries, diesels have huge presence in Europe's passenger cars. Nevertheless, Mercedes' economies of scale reaped by commonizing hardware between European- and U.S.-bound vehicles allow diesel sticker shock to be minimized.

The right choice
For 2007, all E-Class models sport mildly tweaked styling. It's hard to spot the changes. Look closely and you'll find a deeper airdam and a new front bumper, resulting in a pointier nose and more pronounced intakes at the corners. The headlights, taillights and rear bumper are new, too. Overall, the look remains dignified, if generic from the rear. The only way to distinguish a Bluetec from an E350 (besides the badge, of course) is by its smaller wheels — the Bluetec rides on 16-inchers with 225/55 tires instead of 17s with 245s. As a result, the Bluetec wears 12.3-by-1.1-inch front brakes, the smallest of any E-Class model.

In some respects the 2007 Mercedes-Benz E320 Bluetec renders the company's E350 redundant. It offers a similar driving experience at a similar price, and in the bargain you get the Bluetec's bladder-busting 700-plus-mile range, and much better fuel economy. Neither one is a hard-core back-road burner, so if you've got a $50-grand craving for an E-Class and live in the right state, we say skip the E350 altogether in favor of the Bluetec. By nearly any measure, the Bluetec acquits itself as the entry-level E-Class of choice.

Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.