I'm personally a big fan of diesel-engined passenger cars. As a market, we seem not to care, but modern diesel engines are perfect for American driving practices. They have loads of low-end torque and get great mileage on the open road even with heavy loads.
We've been excited to drive the new Mercedes diesels, because they combine legendary Mercedes refinement with fantastic economy and serious thrust. I'm convinced that if you put ten people behind the wheel of an E320 Bluetec, nine of them won't even notice that they're driving a diesel. It's that smooth and quiet.
Oh, and it's fast. Seriously fast. Full throttle in 2nd gear keeps the traction control working. Standing-start burnouts are as easy as holding the brake with your left foot and dialing in half throttle with your right. Diesel burnouts? YEAH!
Let go of the brake pedal, and the E320 Bluetec's 3.0-liter diesel will catapult it to sixty in 6.6 seconds. That means it'll blow the doors off of last year's E320 with the gas engine!
This year's gas-engined six-cylinder E-Class, the E350, gets to sixty in about the same amount of time, even though its engine is a half liter larger. The big difference is in fuel consumption. Instead of gliding down the highway eating up a gallon of gasoline every 26 miles, the E320 Bluetec sips a gallon of diesel every 37 miles. And unlike hybrids, which do much better on EPA tests than they do in the real world, you can really expect to see that kind of fuel economy on the highway.
So the diesel is just as fast as the gas car, even with a half a liter less displacement, and it gets significantly better fuel economy. Is there a downside? Yes, but fortunately it's small.
Our E320 Bluetec is really slow off the line. From idle to about 2000 rpm, there is practically no throttle response. Strangely, the ML320 CDI that we have in the office now, too, ses a similar engine and doesn't suffer from this problem... it rockets off the line with sports-car alacrity.
We've contacted Mercedes, and they confirmed that there are some subtle differences between the two engines. The ML's diesel is rated with slightly more power and torque (215 hp and 398 lb-ft, respectively, compared with 208 and 388), and doesn't meet the same emissions standards. They weren't, however, able to explain the sluggish throttle response.
We're hoping that it's something affecting only our particular car, because it's literally the only negative in a win-win equation from Mercedes.
