More Details on BMW Hybrids
BMW’s X6 and 7 Series hybrids, which debuted in concept form at last November’s L.A. auto show, will likely arrive late this year and in early 2010, respectively. Do we need hybrid versions of leather-lined luxury cars? That's debatable, but Lexus and Mercedes are forging ahead with ‘em, so why not BMW, too? At yesterday’s Washington, D.C., auto show, we learned a few more details on both.
The X6 hybrid is a “full” hybrid, using the two-mode technology co-developed by BMW, Chrysler, Mercedes and GM. That means it can scoot on electric power, gasoline power or a combination of the two. And scoot it will — the powertrain works with the X6 xDrive50i’s 4.4-liter, turbocharged V-8. BMW VP of engineering Tom Baloga said to expect 20% better overall gas mileage, so combined city/highway gas mileage should work out to 18 mpg, versus the gas-only model’s 15 mpg. Compare that to the Mercedes-Benz ML320 Bluetec (20 mpg) and new Volkswagen Touareg 2 V-6 TDI (estimated low 20s). We should note that both are diesels, and as of yesterday diesel fuel was about 29 cents — 14% — more per gallon than premium unleaded. (What’s more, if you’re looking for top mileage among luxury SUVs, the less-expensive 2010 Lexus RX 450h should get a combined 27 mpg with AWD.) The X6 Hybrid should also be fast as stink.
The 7 Series, meanwhile, will be a “mild” hybrid. The transmission-mounted electric motor can add up to 20 hp to the 750i’s 4.4-liter, turbocharged V-8, but it doesn’t allow the 7 to run on electric power alone, nor will it allow the engine to shut off at idle, something several other mild hybrids allow. The lithium-ion battery — an advanced energy source, considering older nickel-metal hydride batteries are still the choice du jour — powers the system. It sits in the trunk in place of the spare tire, and Baloga promised minimal intrusion on luggage room. BMW “hasn’t run certification tests yet,” he said, but the system won’t reap the same 20% gains as the X6’s full hybrid system.
In other fuel-efficiency news, Baloga said there are still “single-digit” percentage gains to wring from the conventional gasoline engine, even as automakers have eked out all they can from internal combustion technology. But it won’t be easy.
“The low-hanging fruit has already been picked,” Baloga said. “Further technology comes at a significant cost,” especially if it doesn’t directly alter mpg window stickers. Right now, the EPA doesn’t test for features like start/stop technology or navigation systems that route you based on optimizing gas mileage. BMW is lobbying to change that, but in the interim it makes investments in such features “a very tough business case,” Baloga said. At the end of the day, it seems, unless an efficiency technology can nudge that city or highway figure up a tick, it may not make it past the drawing board.