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The retractable hardtop is also a nice feature, despite the extra weight. Weekend track drivers will want to opt for the carbon-fiber roofed Coupe to reduce weight, but the M3 Convertible works as a more multipurpose car, allowing open-top driving in good weather. We found the top was a bit slow in moving up and down, and it seriously compromises trunk room, but having it down lets you hear the engine much better than you can with it up. The sound of the engine changing speeds with gearshifts was particularly enjoyable.
Under the hood
With the BMW M3 Coupe, we reveled in its power and handling, sticking to third gear, with its wide power band, as we slung the car around corners, feeling the rear come out just enough so that the front was pointed in the right direction. Although a convertible top compromises performance, BMW engineers kept it to a minimum in the M3 Convertible. We did most of our hard driving with the top up, to keep the weight balanced properly, and found little difference between the two cars on public roads.
We took the car on the same route we drove the M3 Coupe, a series of long, winding roads north of San Francisco, then back down along the coast on Highway 1. The double-clutch transmission definitely changed the driving experience--we kept it in manual mode and spent more time shifting between second gear and third gear than we did with the manual transmission M3 Coupe, which was content to run in third gear for all but the tightest turns. Shifting with the DCT is effortless, merely requiring a pull on the left paddle for downshift and the right for an upshift.
As an M car, the M3 Convertible has a power button on the console. The car moves forward sluggishly with it off, requiring you to practically floor the gas pedal. Given this behavior, we're not sure if leaving it off improves fuel economy. Leave it on, though, and the throttle response sharpens considerably, giving the feeling that you've suddenly gained 50 horsepower. The 4-liter V-8 engine is a remarkable piece of engineering, using BMW's Double-VANOS for valve control, with individual throttle control for each cylinder. The result is 414 horsepower at 8,300rpm and 295 foot-pounds of torque at 3,900rpm.
Our car also had the optional electronic damping control, which gives the suspension three modes: comfort, normal, and sport. EDC should be a standard feature on the M3, as it seems like a crucial bit of tech to improve the car's handling. Comfort loosens the suspension up a little, giving a slightly softer ride. We relied on normal mode for much of our driving, as it automatically adjusts the suspension damping to your current driving style. We could feel the difference in handling when we went from diving into corners to cruising down the highway. One option our car didn't come with was the programmable M button, which lets you set the car for sport driving with a single button touch.
BMW incorporates even more programmable technology into the double-clutch transmission with its DriveLogic settings. A rocker switch on the console lets you change the gearshift response through five settings, shown as one to five bars on the instrument cluster display. You can have different settings for automatic and manual gearshifts mode, and the car will save them, reverting to the proper setting when you put the car in manual mode, for example. At one bar, the shifts feel softer, as the car kicks in a limited amount of torque during the gearshift. With DriveLogic maximized at five bars, the shifts feel harder, as the engine adds the maximum amount of torque the program allows during the gearshift. The difference from one bar to five is a soft push versus a hard punch in the back during gearshifts. We kept it at five bars for manual mode, enjoying the visceral feeling of shifts from second to third, enhanced by amazing engine sounds with the car's top down.
Driving with the double-clutch transmission, we liked the fact that we could keep pressure on the gas pedal while shifting. In traffic, the DCT handled itself well, making smooth shifts at low speeds and pitching no fuss when it had to sit in first gear at a stop light. BMW incorporates hill hold tech into the system, too, so that you don't roll backward during a hill start.
The base price for the 2008 BMW M3 Convertible is a hefty $66,150, and that's missing much of the tech we've mentioned. Two features adding significantly to our car were the electronic damping control, for $1,000, and the double-clutch transmission, for $2,900. BMW Assist, which brings in telematics and Bluetooth, adds $750. Other nontech options and an $825 destination fee brought the total up to $72,925. Cabin tech options we would have chosen for the car would have been navigation, enhanced audio, and iPod integration, which would have added $4,400 to the price, putting our convertible sports car close to $80,000. Getting the convertible adds a pretty serious premium to the price of a standard M3, but few other companies make convertibles that perform this well.
The M3 Convertible earns our top rating for performance, with the superb engine tech, DCT, and EDC all contributing to a sublime driving experience. Although our test car didn't come with much cabin tech, we give it credit for the optional navigation and audio systems, for a strong score in this category. Design is also very good--the car looks as good as it drives.