No More Acceleration Problem With BMW M550i xDrive

Last year's refreshed BMW M550i xDrive is more than adequate for most sports sedan buyers. Otherwise, the M5 is available. The 4.4-liter twin-turbo V8 in the latter is good for 523 hp and 553 lb-ft of torque. However, when the sedan was evaluated by Car and Driver a few months ago, they detected something.

While it takes 4.1 secs to accelerate from 0 to 60 mph, it is still 0.2 secs slower than the X5 M50i, which shares an engine and is 856 lbs heavier as a result of this. A high-octane 93 fuel fill-up was the first move towards solving the problem.

The sprint time was reduced to 3.9 secs, however, BMW believed a time of 3.6 secs was attainable. BMW took notice of its inability to attain a sub-3.9-second time and swiftly put its engineers working. It didn't feel quite right. Sure, there was an issue.

A previously unrecognized software flaw was discovered, resulting in a communication breakdown between the motor computer and the stability-control unit. During a standing-start launch, the stability control intervened, telling the motor to cut force.

As a result, the car was unable to produce the full 523 horsepower, attaching a few tenths of a second to the time it took to reach 60 mph. This affected not just the BMW M550i, but also the 540i xDrive. BMW has informed customers that an over-the-air upgrade fix is now provided. The car's revised 0-60 time is now 3.5 secs and the quarter-mile time at 119 mph in 11.8 secs.

If you're looking for the ultimate driving machine, you'd better pay attention to the tiniest of details. It's all in the details.