Our car came with the Premium Sound option, which includes two subwoofers and a digital signal processor. Along with the normal bass and treble audio settings, BMW includes a full seven-band graphic equalizer buried under the audio settings menu. The sound quality from this system is good, but we weren't blown away. The system produces a very heavy sound, which dulls the highs. Bass is strong, but not sharp.
The other significant tech option on our car was Bluetooth cell phone integration, which comes with the BMW Assist telematics package. The phone part of this system works very well, immediately downloading a compatible phone's contact list and making it available through the iDrive interface. The telematics side of BMW Assist offers roadside assistance, automatic collision notification to a central office, and recovery services for stolen vehicles.
Under the hood
Driving the BMW 128i Convertible was not nearly as fun as the 135i. Acceleration felt strangely uneven, but we couldn't determine if that was becuase of difficulty modulating the gas pedal, the transmission, or the engine itself. With a hard foot on the gas pedal, the car delivers reasonable acceleration but no tire-spinning theatrics. The six-speed automatic transmission keeps potential antics under control, although in manual mode it lets you run the tachometer close to redline.
In spirited driving over mountain roads, we felt some lean as the inside shocks extended, very unlike the more planted feel of the 135i. As our 128i came with the Sports package, bringing in a sport-tuned suspension, we were a bit surprised at this behavior. The steering was very responsive, as we would expect from a BMW. As a convertible, we would expect the 128i's driving performance to be a bit compromised, but the body didn't feel like it lost any stiffness. The car feels more like BMW softened the suspension, designing it for the general public as opposed to driving enthusiasts.
For power, BMW deploys its latest engine technology in the 2008 128i Convertible, giving it the same straight six 3-liter engine found in the 328i. This magnesium-aluminum engine uses BMW's continuous variable valve timing system, called Double-VANOS. It puts out a modest 230 horsepower at 6,500rpm and 200 foot-pounds of torque at 2,750rpm. In the 135i, this engine gets dual turbochargers, but in this application, it is naturally aspirated. BMW claims 7 seconds to 60 mph.
The car gets an EPA-rated 18 mpg in the city and 27 mpg on the highway. During our time with it, doing a variety of city and freeway driving, we came in at a solid average of 21.3 mpg. For emissions, the 128i meets the California Air Resources Board's ULEV II rating, a very good achievement.
The base price for the 2008 BMW 128i Convertible is $33,100, about $5,000 more than the 128i Coupe model. But BMW options are expensive, quickly jacking up the price with most of the features we've mentioned here. The Premium package added auto-dimming mirrors, telematics, and Bluetooth, for $3,600. The automatic transmission added $1,275, while the sport steering wheel with paddle shifters cost an additional $100. The navigation system was $2,100, HD radio cost $350, Sirius satellite radio was $595, and Premium sound cost $875. The Sport package, which added the sport suspension and 17-inch wheels, added $1,200. A few other options and a $775 destination charge brought our total up to $46,895, a lot of money for a relatively small convertible. The closest alternative to the 128i Convertible is the , but that's a more expensive car with inferior tech.
For cabin tech, the navigation system mostly impresses with its live traffic feature. The stereo was OK, and we liked its iPod integration, but we didn't think it really sounded "Premium." The phone system is very good, though, earning the 128i Convertible a decent rating. Performance tech is certainly better than average, but we felt this car lagged behind other BMWs we've tested. For design, the car suffers from its iDrive interface, and the body style doesn't regain much ground.