2007 Mercedes-Benz E-Class

Nearly half the cars in Europe have modern diesel engines largely because of stiff fuel prices for gasoline, but the diesel has been a rarity in autos sold in America—despite stiff gas prices last summer and an uncertain future gas price situation.

Blame the lack of enthusiasm for diesels in this country on fairly cheap gasoline and a bad taste left in mouths of Americans by a disastrous General Motors attempt some years ago to sell diesel cars. They had smelly, dirty, poor-performing gas engines converted to diesel designs in response to a fuel crisis.

Enter the 2007 Mercedes-Benz E-Class E320 BLUETEC diesel sedan, which is a luxury car that weighs a hefty 3,860 pounds. Its modern, turbocharged V6 diesel engine delivers V8 performance with 4-cylinder fuel economy and provides a range of more than 700 miles on a single tank of fuel.

Major automakers are working on developing modern diesels for sale in America, but Mercedes is the first to offer a car with such a diesel here. That shouldn't be surprising because Mercedes sold the world's first production diesel car in 1936 and has been perfecting the diesel engine ever since.

Some may have forgotten that about 75 percent of Mercedes cars sold here in the 1980s were diesel-powered. But few cared what was under a Mercedes hood then because the automaker's only direct rival was Cadillac. Mercedes diesels also had a reputation for lasting practically forever.

The E320 BLUETEC has a low-emissions diesel, so its name suggests clear blue skies and high technology.

That's a Diesel?
A media preview of the E320 BLUETEC involved several hundred miles of driving over a variety of roads outside Las Vegas. The E320 BLUETEC showed most won't be able to tell that the E320 BLUETEC is a diesel car except for a muted characteristic diesel engine sound heard when standing near the hood when the engine is idling. I found that sound vanished when the E320 BLUETEC got under way—even during 90 mph cruising on rural Nevada roads.

The E320 BLUETEC diesel thus has banished the smell, smoke, clattery noise and slow starting and acceleration of 1980s diesels.

Only a "BLUETEC" badge on the trunk lid visually identifies the E320 BLUETEC, which has an engine significant enough to distinguish this car from gas versions of the E-Class.

Quiet and Smooth
The quiet, smooth E320 BLUETEC delivers an impressive, estimated 37 mpg on the highway and 26 in the city. Standard fuel economy ratings for the E320 BLUETEC top those for a hybrid of comparable size and power.

The highest estimated economy figures for a 2007 E-Class gasoline-engine sedan are provided by the 268-horsepower V6 version, which delivers 19 mpg in the city and 26 on the highway.

The E320 BLUETEC has a 21.1-gallon tank, so its driver won't spend much time at fuel stations. Mercedes estimates you'll go about twice as far between refueling stops on long trips as a typical gas-powered car, depending on the size of an auto's fuel tank. Around town, you're likely to fill up your diesel Mercedes just three times a month, while your neighbor with a gas car will likely fill up at least twice weekly.

Realistic Economy Figures
EPA-estimated diesel economy figures generally are closer to real-world figures than estimated numbers for regular gasoline-engine cars—and even gas/electric hybrid autos. Diesels even top EPA numbers under certain conditions.

That fact has recently led some industry analysts to predict that diesels will become more popular than gas/electric hybrids in America. Diesels deliver roughly the same fuel economy as hybrids, many of which are considerably more costly than gas-engine cars.

No Big Price Penalty
The $51,550 E320 BLUETEC only costs $1,000 more than the standard entry-level E320 gasoline engine E-Class.

However, Mercedes officials said at the E320 BLUETEC preview that the automaker isn't giving up on hybrid vehicles. They said that a diesel/electric hybrid will be more effective than today's gasoline/electric hybrids.

Cleaner Diesel Fuel
Americans haven't been exposed to major improvements made to the performance and refinement of diesel engines. The hang up here has been the lack of cleaner low sulfur diesel fuel.

Without such fuel, the E320 BLUETEC couldn't meet low emissions standards. However, because of a federal mandate, the cleaner new diesel fuel, which contains less than 15 ppm sulfur content, recently became available across America. The old sulfur content in diesel fuel was 500 ppm, so sulfur has been reduced by 97 percent.

How It's Done
The E320 BLUETEC diesel uses several coordinated technical measures to minimize emissions within the engine and provide for effective exhaust gas treatment. Used are such items as an oxidation catalytic converter and a particulate filter, along with new techniques for reducing nitrogen oxide emissions.

The E320 BLUETEC initially is being sold in 45 states. Mercedes is negotiating with clean air officials to sell the car in California and several Northeastern states, which have stricter emissions regulations.

Ace Up Sleeve
But Mercedes has an ace up its sleeve in the form of AdBlue injection. AdBlue is an aqueous carbamide solution injected into the engine exhaust flow. Ammonia consequently is released to reduce nitrogen oxides to harmless nitrogen and water in a catalytic converter. The AdBlue tank needs to be refilled only during regular maintenance checks.

The E320 BLUETEC diesel develops 208 horsepower—but also nearly 400 foot-pounds of torque. That tops the torque rating of most V8 models.

Fast Acceleration
The E320 BLUETEC does 0-60 mph in 6.6 seconds, which allows it to out accelerate the V6 gas-engine E-Class Mercedes. A smooth, responsive 7-speed automatic transmission enhances fuel economy and performance.

Where can you get diesel fuel? At least 42 percent of all fuel stations offer such fuel for diesel-engine SUVs, pickup trucks and such cars as Volkswagens—not to mention older Mercedes diesel models. Some 80 percent of fuel stations initially must offer the new Ultra Low Sulfur (ULSD) fuel required by the E320 BLUETEC.

Diesel Filling Stations
That means up to 76,500 filling stations in America and Canada could carry the new fuel in the first phase of its introduction. Mercedes will inform an E320 BLUETEC owner of the nearest diesel fuel station if he or she can't find it.

Many may feel that the E320 BLUETEC is worth taking a little more time to find a diesel fuel filling station.