From Consumer Reports:
September 18, 2008 Driving Euro diesels from Audi, BMW, Chrysler, and Mini More than half the cars sold in Europe are high-mpg diesels. So given the opportunity to sample four models directly from the Continent, we hoped to find out if modern European diesels are good enough to entice American drivers.
Small-displacement engines with big torque and fuel economy numbers have long been considered forbidden fruit to the U.S. market. With the revised, ultra-low-sulfur fuel recently adopted in the States, we are seeing a slow influx of European diesel models reach our shores. Mercedes-Benz and Volkswagen have lead this wave of new diesels, and several other automakers have announced plans to bring more here.
So, what do we have to look forward to? We got a taste last week by attending the annual International Motor Press Association (IMPA) track days at Pocono Raceway, where we piloted several imported diesel models provided by Bosch. We sampled four European-market diesel models: 2009 Audi A4 3.0 TDI Quattro, 2007 BMW 123d hatchback,
2007 Chrysler 300D, and 2008 Mini Cooper D. (Bosch supplies some of the fuel injection and emissions control equipment for these cars that allow them to meet stringent air quality standards in Europe. They say the cars could also be made 50-state compliant in the U.S.)In our review of the Mercedes-Benz E320 Bluetec diesel last year, we raved that its modern diesel engine was not only clean, but also felt as smooth and powerful as a gasoline engine. (Watch our video road test.)
In driving the four European cars at IMPA, it is clear that modern diesels are much smoother and quieter than those engines Americans may remember from the 1980s. But not all are as refined as gas engines, or as that E320.
I was very impressed with the Audi A4 3.0 TDI. This A4 has 236 hp and a whopping 369 lb-ft of torque, giving it impressive acceleration. The car was also quiet, relaxed, and refined in driving on the street. It?s rated at a combined 36 mpg on the European fuel economy test cycle. And several of us came away from a lap around the road course wearing wide smiles.
The Mini Cooper D gets impressive fuel economy (rated at 60 mpg combined on the European fuel economy test cycle). The Cooper D driven at Pocono didn?t require as much shifting as our base Mini Cooper with a manual transmission to stay in the power band, but it had a notably gruff engine sound. The same was true for the torquey and entertaining BMW 123d hatchback, which was rated at 45 mpg overall. Both the Mini and the BMW included an auto-stop feature that shut the engine off when the car was stopped to avoid wasting fuel when idling.
Bosch tells us the Chrysler 300D uses the same
3.0-liter V6 diesel engine as the Mercedes we tested. It was plenty powerful in the Chrysler, but not as smooth as in the Mercedes. (Also, we smelled diesel fumes after making a U-turn, whereas we couldn?t smell a thing in the Mercedes, even with our nose near the tailpipe while it was idling.) It?s rated at 35 mpg overall.In the end, the lesson is that while modern technology has dramatically reduced diesel vibration and sluggishness, they aren?t as smooth as the best gas engines. Powertrain noise and vibration suppression are a combination of engine design, noise reduction under hood, and engine mounting technology. Nevertheless, the sacrifices to drive a diesel are much smaller than they once were, making the fuel economy improvements and abundant torque all the more compelling.
Now if only diesel fuel prices were closer to regular gasoline?
?Eric Evarts