Reviews

2012 BMW 640i Driving Impressions


The BMW 640i is a very sweet car to drive. The engine is incredibly smooth and sounds nice, a heavily subdued if not sedated scream when you're on the gas, or silent when you're just cruising. Its 330 foot-pounds of torque are available from 1400 to 4500 rpm, and what more do you need? With 315 horsepower and that much torque, you've got all the acceleration that real-world driving demands. The 0 to 60 time is about 5.4 seconds, and that's quick.

The 8-speed ZF manual automatic transmission with paddle shifters does it all. The top two gears are serious overdrives, with long-legged ratios of 0.839:1 and 0.667:1, so the freeway rpms are way low. Driving casually in automatic mode, the upshifts are seamless and kickdowns relatively infrequent; the transmission is programmed to use the engine's torque.

In effect, it's a close-ratio 6-speed, and, using the paddles, you can play with it like that. It will respond sharply and obediently. It will deliver hard downshifts, and will short-shift upward when you want it to. It upshifts at 5800 rpm by itself in manual mode, and it upshifts at the same rpm every time, it doesn't second-guess the driver. We rarely are able to make those statements about automatic transmissions, not even the sportiest of them.

Our 640i test car was not equipped with the optional Active Roll Stabilization, which reduces body roll in corners and transition. Sensors calculate the degree of body roll and trigger hydraulic rotary actuators in the front and rear anti-roll bars, for flatter cornering.

Nor was it equipped with Integral Active Steering, which combines the Active Steering system for the front suspension with a steerable rear suspension. Precisely harmonized steering movements of the front and rear wheels create a virtual lengthening or shortening of the vehicle's wheelbase, which improves high-speed stability and enhances maneuverability for both parking and city use. It's magic, invisible technology.

One important thing is that the ride in Sport mode was not harsh, while the transmission shifts came more quickly and throttle response was sharper and steering quicker; but it's not noticeably aggressive, so comfort isn't compromised. But the Comfort mode is neither soft nor lazy, so it's good to stay in when you're not feeling sporty in the curves.

The brakes are pretty much impeccable, using massive vented discs. The pedal has a nice touch, and brings the 640i to smooth stops from high speeds or around town. The braking system is linked to the electronic stability system. There's also a regenerative feature, which captures electric energy during braking and transfers it to the battery, reducing alternator drag.

Last but not least, the Auto Start-Stop function is a pain, and not just to us, because BMW forums aggressively criticize it. It doesn't just intrude at red lights and stop signs, but it keeps shutting the car down in stop-and-go city traffic; every time you move forward three feet, you hear the starter crank and the engine fire, and you feel a slight jerk in the brake pedal. We might go for this feature if it somehow knew when you were going to be stopped for maybe a minute or more, but not when it keeps stopping the engine every time you stop the car. And it's not the stop but the start-up that's annoying.

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