2007 Mercedes-Benz E-Class

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2005 Mercedes-Benz E320 CDI

This 2005 review is representative of model years 2003 to 2009.
By Ann Job of MSN Autos
Rating: 9.5
Pros:
  • Luxury ride
  • Awesome torque
  • Fuel efficiency
Cons:
  • Finding better-quality diesel
  • Limited numbers available
  • Priced a bit higher than comparable gas model

I managed to get more than 40 miles a gallon while driving a Mercedes-Benz E-Class sedan.

I wasn't traveling all downhill, I didn't putter slowly to my destination about 109 miles away, and no, this wasn't an experimental car.

It was the new, 2005 Mercedes E320 CDI, the first Mercedes diesel-powered car offered in the States since 1999.

An early 2005 model, the E320 CDI boasts impressive fuel economy. In fact, my fuel-stingy drive segment produced better results than even the government's official rating for the car of 27 miles a gallon in city driving and 37 mpg on the highway. More about this later.

What also is noteworthy is how quiet and powerful this five-passenger luxury sedan is.

There's nary any of the usual diesel engine clatter, and torque in this new model is an awesome 369 lb-ft at 1800 to 2600 rpm.

Meantime, the price premium for this six-cylinder diesel model at introduction was just $1,000 more than a 2004 Mercedes E320 with gasoline six cylinder, for a starting manufacturer's suggested retail price of just over $49,000.

Diesel drawbacks
I know. You're thinking a diesel has to be loud, smelly, sluggish and polluting. These are longstanding complaints about diesels.

But diesel technology, like the common-rail direct injection system used by Mercedes, is bringing big improvements.

CDI, as it's referred to at Mercedes, provides a common rail, or line, to deliver fuel at a constant, incredibly high pressure—23,000 psi—to all fuel injectors in the 3.2-liter inline six simultaneously.

Meantime, the electronically controlled injection system puts the fuel directly into the cylinders. The electronics help vary injection timing and the quantity of diesel fuel based on power demands of the driver and emission control.

The direct rail and electronic fuel injection combination also eliminates much of the diesel racket associated with old-style diesel engines. Additionally, it helps reduce emissions and diesel exhaust smells and gives the E320 CDI its palpable low-end torque.

Rocket ready
There's no sluggishness when driving this car. The engine has a turbocharger and intercooler for strong power delivery, and so this sizable, regular-looking Mercedes sedan can zip from 0 to 60 miles an hour in 6.8 seconds, which is 0.3 second faster than the naturally aspirated, six-cylinder, gasoline-powered E320 sedan.

As you'd expect in a diesel, the torque comes on at very low engine rpm—1800 rpm—so drivers feel as if there's virtually no waiting before this relatively heavy and solid-feeling car rushes forward. It feels surprisingly sporty, yet controlled.

I had my back pressed into the seatback plenty of times while driving this car, and I never lacked for power to zip into traffic, pass on two-lane roads and accelerate and merge onto freeways.

Note the torque is 59 percent greater than the 232 lb-ft at 3000 to 4800 rpm that's generated by the gasoline engine that's in the 2004 E320 sedan.

Horsepower, however, of 201 in the E320 CDI is less than the 221 horses in the gasoline-powered E320, though in the test drive, I never felt like the car was tapped out on aggressive highway runs.

There is only one transmission in the CDI car—a 5-speed automatic with a shift-it-yourself feature that doesn't require a driver to use a clutch pedal.

Working on pollution
I didn't catch a whiff of the usual diesel odor at the back of the test E320 CDI, and there wasn't any visible exhaust smoke as I've noticed on some older-model diesel vehicles.

Yes, the diesel technology helps here, too. But so does "good" fuel—diesel that has lower sulfur content and lower concentrations of aromatic compounds such as cyclic and polycyclic hydrocarbons.

Bharat Balasubramanian, vice president of engineering technologies and regulatory affairs at Mercedes Car Group Development in Germany, suggested consumers in the United States still have to shop around to find the best diesel fuel because sulfur content can vary.

U.S. regulations require it to be no more than 350 parts per million in diesel fuel sold here. But it won't be until September 2006 when so-called "clean" diesel fuel with sulfur levels of 15 ppm is required at every diesel pump.

Mercedes officials expect that until then, the E320 CDI can be sold in 45 states but not in New York, Maine, Vermont, Massachusetts and California, where pollution regulations are the strictest.

Luxury character
I kept trying to hear the diesel at work, but the interior of the CDI model seemed as quiet as it is for a regular E320.

In fact, Mercedes reports that at idle, sound levels inside the E320 CDI interior are at 44 decibels vis-a-vis 42 decibels in a gasoline-powered E320. At full throttle, the CDI car is quieter inside—72 decibels vs. 76 in the gasoline-powered car.

Even when I stopped the test sedan, got out and went to the front to listen after running the test car hard, I didn't hear a big diesel engine ruckus.

Much in common with gas models
Mercedes didn't change the already capable handling and ride of the E-Class when it added the new powerplant.

The car's suspension and steering continue to allow for spirited driving on mountain roads as well as comfortable in-town travel. Front and rear seats continue with a good amount of room for up to five passengers.

Trunk space remains at 15.9 cubic feet, and luxury amenities abound, as they do in all E-Class cars. They include standard leather-surfaced seats and wood accent trim, dual, automatic climate control, surround sound audio system, 10-way power front seats, power windows, door locks and mirrors as well as Tele Aid emergency notification system and frontal, side and curtain airbags.

Be aware, though, that Mercedes plans only 3,000 diesel sales in calendar 2004, so supplies of the E320 CDI won't be plentiful. Officials said they hope to increase the supply in 2005.

Fuel economy run
The fuel tank of the E320 CDI is 21.1 gallons, which is a half gallon more than in the gasoline-powered sedan.

This fuel capacity and the exceptional fuel economy of this new model—it's 39 percent higher than the comparable gas-powered E320—mean drivers won't have to stop to fill up for some 600 miles of combined city/highway travel, even if they get something close to the government-rated fuel economy of 32 mpg in combined city/highway driving.

It's enough to travel from New Orleans to Nashville or Charlotte, N.C., to Indianapolis on a single tank or go roundtrip from Dallas to Little Rock.

But getting more than 40 mpg, like I and my navigator did, took some extraordinary, fuel-saving efforts.

On a sunny, 80-degree day, we agreed to keep windows closed and the air conditioning turned off—at least until we both began sweating inside the car. Then, we alternated driving with the AC on, then off.

We also shifted into neutral and coasted whenever we came down a hill on two-lane, country roads.

We used a different strategy when we got on the highway, though. We sought to draft behind large vehicles—in actuality, tucking closely behind a pickup truck towing a camper, and later getting behind a semi. But this meant we couldn't see much ahead of us, and we were required to match the speed of the bigger vehicle directly in front.

Once we got into the city, we worked to minimize stops by coordinating our speed with upcoming stoplights.

Other auto journalists got even better fuel economy in the E320 CDI.

Like us, they kept the AC off and windows up. Unlike us, they never went above 60 miles an hour, even on the highway, and so took up to 20 more minutes to travel the same route.

It all depends on how you measure efficiency. We figure we were efficient with both time and fuel, achieving just over 40 mpg with an average speed of 57 mph while arriving at the destination in one hour, 54 minutes.

Not bad for an afternoon's drive.

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BB02 - 9/20/2014 7:36:09 PM