2005 Mercedes-Benz E320 CDI

Interior accommodations are no different: elegant, spacious, driver-oriented.

Built around a Common-rail Direct Injection system, the new engine is "cleaner, quieter, more powerful," Markris said, "using very high pressure." In fact, internal pressures approach 23,000 pounds per square inch. Diesel engines do not require spark plugs, as they rely on pressure to compress the fuel/air mixture inside each cylinder. They use glow plugs, which are said to operate a lot faster than in diesel's earlier days.


Operating with full electronic fuel injection, the E320 CDI's engine produces 201 horsepower at 4,200 rpm, and a whopping 369 pound-feet of torque through the range of 1800 to 2600 rpm. That's enough to yield 0-60 mph acceleration in an estimated 6.8 seconds, which is slightly quicker than an equivalent gasoline-powered E-Class sedan that uses a 271-horsepower engine with far lower torque output.


Mercedes-Benz has the figures to show that the diesel engine is actually quieter than its gasoline equivalent, and claims that exhaust smoke is no longer visible. The Environmental Protection Agency estimates that an E320 CDI will achieve 27 miles per gallon in the city, and 37 mpg in highway driving. In contrast, the gasoline E-Class is rated at 19-mpg city and 27-mpg highway.


Fuel is injected directly into cylinders, not into the intake stream, said Prof. Dr. Bharat Balasubramanian, vice president of engineering technologies and regulatory affairs. This produces "very high torque at very low speeds," so you can drive without downshifting on hilly roads. Mercedes-Benz claims that those who drive 10,000 miles per year can save 160 gallons of fuel.