Under the Hood

The 640i is powered by a 315-horsepower, turbocharged 3.0-liter six-cylinder engine. Its peak torque rating is 332 pounds-feet. BMW cites a zero to 60 mph time of 5.5 seconds for both the coupe and convertible. The standard eight-speed automatic transmission includes steering-wheel-mounted shift paddles.

Other standard features include computer-controlled adaptive shock absorbers and Driving Dynamics Control, which allows the driver to adjust the ride quality, accelerator response, power-steering assist level and automatic transmission behavior.

Optional mechanical upgrades include active stabilizer bars and active steering, the latter of which adds rear-wheel steering to the earlier generation's variable-ratio front steering system.

    See also:

    Tire tread
    Summer tires Do not drive with a tire tread depth of less than 0.12 in/3 mm. There is an increased danger of hydroplaning if the tread depth is less than 0.12 in/3 mm. Winter tires Do not driv ...

    Hydroplaning
    On wet or slushy roads, a wedge of water can form between the tires and road surface. This phenomenon is referred to as hydroplaning. It is characterized by a partial or complete loss of contact ...

    The concept
    The system is functional at speeds beginning at approx. 20 mph/30 km/h. The speed specified using the lever on the steering column is maintained. The system brakes on downhill gradients if engin ...