BMW Z4 M, minus the M

BMW shows off a tweaked version of its Z4 roadster at the 2010 Detroit auto show.

BMW cranks even more power out of the twin turbo-charged engine in its Z4. BMW

The BMW Z4 sDrive35i is an excellent sports car. However, BMW's engineers, who must experience self-critical dreams every night about how much smoother a valve could be or whether changing the timing of a spark by a millisecond might improve combustion, couldn't leave it as is. They developed the 2011 BMW Z4 sDrive35is, a higher performance version of BMW's roadster.

Like the sDrive35i, the new roadster uses a twin turbo 3-liter straight six cylinder, but BMW fitted it with a new twin turbo unit to crank up the horsepower from 306 to 335, with torque up from 295 pound-feet to 332 pound-feet. This engine tweaking gives the sDrive35is acceleration to 60 mph in 4.7 seconds.

Beyond the engine work, BMW tuned the exhaust to give a more pleasing, sports car sound. Baffles and mufflers combine to give the car what BMW describes as a "deep rumble with a focus on the low frequency sound range." People will be surprised when they see a little roadster following that exhaust note as it works its way up the street.

The sDrive35is also gets BMW's seven-speed double-clutch transmission, a manual with two computer-controlled clutches. The driver can choose an automatic mode or shift manually, but doesn't have to push a clutch pedal. The result is no power loss at the wheels during shifts.

You can even get the car with some M equipment, including an adaptive suspension that uses electronically controlled shock absorbers to counteract roll and keep the tires gripping pavement. That's a lot of tech in a little car.

BMW will show the Z4 sDrive35is at the upcoming 2010 Detroit auto show.

About the author

Wayne Cunningham reviews cars and writes about automotive technology for CNET. Prior to the Car Tech beat, he covered spyware, Web building technologies, and computer hardware. He began covering technology and the Web in 1994 as an editor of The Net magazine. He's also the author of "Vaporware," a novel that's available as a Nook e-book.


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