2009 BMW X5 xDrive35d

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What is it?
2009 BMW X5 xDrive35d

What's special about it?
If the idea of a diesel-powered sedan like the new BMW 335d is too hard to swallow, maybe the 2009 BMW X5 diesel will make more sense to you. After all, it weighs 2.5 tons, so it could use a little extra engine torque. And it's a truck, sort of, so you won't look nearly as silly when you pull up to a pump at Big John's 24-hour Truck Spa on your next road trip.

Then again, the real draw of diesel engines is the fact that you don't have to stop for fuel as often, and the 2009 BMW X5 xDrive35d (as it's so clumsily named) delivers on this promise, at least according to its preliminary mileage estimates. At 19 mpg city and 25 mpg highway, the diesel X5 easily tops the standard X5 3.0si with its 3.0-liter inline-6 gasoline engine rated at 15 mpg city and 21 mpg highway.

This is an impressive bump in efficiency, especially when you consider that the twin-turbo 3.0-liter diesel in the xDrive35d also delivers better performance. Its 265 horsepower is only a five-notch increase over the gasoline engine's output, but the diesel's 425 pound-feet of torque nearly doubles the 225 lb-ft you get with the 3.0si. BMW says the added power is enough to get the xDrive35d from zero to 60 mph in 7.2 seconds, 0.6 second quicker than the 3.0si.

With so much upside, you might be wondering why BMW hasn't offered diesel-powered SUVs in the U.S. already. Well, dirty diesel fuel has been one problem, but a new mandate for low-sulfur diesel that went into effect last year took care of the issue. Stringent air-emissions laws were the next hurdle, one that BMW has been able to surmount by introducing a complex new emissions-control system.

BMW officially calls it SCR Catalyst with AdBlue injection. The system consists of an oxidation catalyst, a diesel particulate filter and an SCR catalyst. It's the injection of AdBlue (otherwise known as urea, a product of ammonia), within the SCR catalyst that makes this engine clean enough to meet air quality standards in all 50 states.

This system has been the subject of some debate for years now, as it introduces yet another fluid that needs refilling. BMW says not to worry, as the X5's two urea tanks should provide enough AdBlue to last until a typical oil change is needed. It will be added as a part of BMW's standard maintenance program, so you're good for the first 50,000 miles. No word on what happens if you don't fill the tanks after the free maintenance period is over.

What's Edmunds' take?
As long as the price premium isn't too steep, there are few reasons not to choose the diesel X5 over its six- or even eight-cylinder gasoline counterparts. — Ed Hellwig, Senior Editor