Power, fuel economy seal the diesel
BEFORE you even start, no, you can’t have it. The BMW 330d -- powered by a hugely entertaining 3.0-liter twin-turbo-diesel that gets about 40-plus miles per gallon -- isn’t sold in the United States. But it could be, with a little grass-roots support. And that’s why Honeywell Turbo Technologies -- the supplier of the variable-vane turbos BMW uses in its diesels -- dropped off one of its engineering mules at the L.A. Times garage. A little marketing never hurt anyone.
A quick update on the state of Euro diesels: Last year, BMW declined to join a technology-sharing agreement with Mercedes-Benz, Audi and Volkswagen on a post-combustion diesel emissions technology, known collectively as Bluetec. Since then, BMW has announced that it too will bring diesels to the U.S. in 2008, in all probability a turbo-diesel X5 and 5-series sedan, powered by a 3.5-liter version of the engine in the 330d. (A company spokesman notes that the engine will fit in nearly everything the company sells in the U.S. short of the 7-series sedan.) Six in 10 BMW’s sold in Europe are diesel; worldwide, the company sold half a million diesels in 2006, so it knows whereof it speaks.
BMW will use its own proprietary post-combustion technology on these cars but will use Adblue -- an ammonia-rich liquid injected into the exhaust stream -- to meet increasingly stringent 50-state emissions standards on NOx, nitrogen oxide.
So consider the 330d a foretaste of Munich oil-burners to come. This engine -- an inline six -- puts out 228 hp, 72 hp less than the twin-turbo, gas-powered 335i. But it churns out a tire-wasting 369 pound-feet of torque at a lowly 1,760 rpm, 69 pound-feet more than the gas engine. If the 335i is champagne, all bright and sweet, straining with effervescence at the cork wire, the 330d is burgundy. The diesel has a dark, full-bodied exhaust note, a deep mellowness as compared to the gas engine’s high-pitched wind song. There is virtually no diesel clatter anywhere, and engine vibrations are all but nil.
The diesel engine is slow to stir just off idle as the turbo lag makes itself felt. But once the rpm rise above 1,600, the car swells behind you like a 20-foot wave and you are off. Mid-range torque is abundant but rev range is not. Unlike the gas-powered 335i that has a torque plateau between 1,800 and 5,000 rpm, the 330D has a relatively narrow range of optimum performance. If you are used to gear shifting by ear, the low-revving 330d will take getting used to.
Zero-to-60 mph times hover in the six-second range, even with two shifts. At cruising speed, the 330d positively loafs along. In sixth gear at 80 mph, the clock is at 1,800 rpm -- almost exactly peak torque. To mat the throttle in these conditions is to be shot out of a diesel-powered cannon.
In the midst of all this raciness, the car gets phenomenal fuel economy. I estimate 40 mpg in my week of mixed driving, in which no horses were spared. Many questions remain: First, like hybrids, diesels have an additional cost associated with them, so the payback depends on how much the diesel premium adds to the vehicle’s cost; that premium could be substantial as manufacturers chase rising emission standards. Second, diesel fuel costs have tracked with, and in places even charged ahead of, gasoline costs, so the cheaper-fuel savings have evaporated. But the performance is there, the fun is there, and the fuel economy is there. It’s only a matter of getting the 330d over here.
