HONDA has spent decades establishing a reputation for fuel efficiency. But nothing in the company’s current lineup, including its Civic Hybrid, can match the mileage of the diesel Accord that I recently tested in and around New York City.
Minus its diesel powertrain, the European-market 2007 Accord that I drove is nearly identical to the car that Honda had been selling in the United States as the Acura TSX. That Accord should give a solid indication of the mileage and performance American consumers can expect when Honda offers a diesel option for the redesigned 2009 TSX.
The Accord — a demonstration car provided by Robert Bosch, the German technology company, to highlight its fuel injectors and other diesel components — returned a remarkable 53 miles a gallon on the highway, 34 in the city and 44 in combined driving. Those miles included a bumper-to-bumper crawl through Manhattan, the worst possible conditions for fuel efficiency.
The model I drove was powered by a 4-cylinder diesel displacing 2.2 liters and producing 140 horsepower and a stout 250 pound-feet of torque — the force that drivers feel pushing them into their seats under acceleration. That huge torque relative to the engine’s size is a main advantage of modern turbodiesels, making them well-suited to small economy cars and to burly S.U.V.’s that need torque for towing and hauling.
The America-bound Acura will use a new version of the 2.2-liter engine that I tested. The engine is notable for meeting 50-state emissions standards with no need to carry an onboard tank of urea, an ammonia-generating solution that other diesels use to scrub smoggy nitrogen oxides from the exhaust. Honda’s patented pollution system generates its own ammonia to fulfill the same mission. While that cleaner emissions system wasn’t installed on the Honda I tested, engineers expect it to have no discernable effect on fuel economy.
As with other diesels I’ve driven recently, the Honda’s frugal highway mileage and versatile power are important advantages over the typical hybrid. The Accord covered the zero-to-60 run in just under 9 seconds in my testing, which doesn’t sound spectacular on paper. But its passing power from 30, 50 or even 70 miles an hour was terrific, as the Honda easily shot past slower cars.
And as more hybrid owners are discovering, their cars deliver little or no mileage gain on the highway. That’s because battery packs and electric motors add several hundred pounds, and the system also contributes negligible energy at freeway speeds.
Also unlike hybrids, which require drivers to go easy on the gas pedal, watch the speed limit and coast when possible to improve the mileage, the diesel Honda delivered brilliant economy with no special effort. Even spirited driving didn’t dent the mileage much. The Accord delivered 50 m.p.g. even during a 75-m.p.h. cruise and 40 m.p.g. when I flogged it like a Nascar yahoo.
The Acura’s only diesel telltale is an idle that’s slightly louder than a gasoline car’s, though it’s not at all obtrusive. There was no trace of diesel smell or black exhaust and except for the enormous diesel decal on the car’s side, my passengers would have been unaware that a diesel was under the hood.
I also recently spent a week with the Audi Q7 3.0 TDI sport utility, which will go on sale in January. That model, with a 3-liter turbocharged V-6, delivered about 25 m.p.g. on the highway. But the Audi’s mileage seemed more fragile than the Honda’s, dropping sharply in city traffic and in spirited driving. That was probably due to its sheer mass; the Q7 weighed more than 5,000 pounds.
Audi also demonstrates the performance possibilities of diesel with its exotic R8 V-12 TDI concept sports car, which I took for a too-brief test drive. That blood-red, all-wheel-drive Audi had a 12-cylinder diesel mounted behind my head, generating 500 horsepower and an astounding 737 pound-feet of torque. Audi claims the R8 will rocket from 0 to 60 in about 4 seconds and reach a top speed of 190 m.p.h., all while delivering 24 m.p.g. Audi has not said whether it will put the car into production.
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