Mountain bikes bearing the names of high-performance cars—among them BMW, Mercedes and Porsche—have been available for several years. Mercedes, in fact, supports a pro mountain biking team, and its bikes cost between $3,500 and $5,000. The rest of these luxury wheels are for those who believe you can't own too many German high-performance vehicles. BMW peddles the least fancy bike, which folds and fits neatly into a Beamer trunk. It sells for $695. The cutting-edge model is the Porsche FS Evolution (right), which matches its four-wheeled counterparts with disk brakes, front and rear suspension, and a high-tech drivetrain, all for a mere $6,000. As sexy a ride as these bikes offer, you still need the mettle to pedal.