Car & Driver Magazine noticed this summer that the new BMW M550i xDrive did not accelerate off the line quite as quickly as the manufacturer claimed. BMW took note and promised to address the issue – here are the results.
Apparently, the sedan needed between 3.9 and 4.1 seconds to get from zero to 96.6 km/h (60 miles per hour), despite the manual claiming 3.6 seconds. A different model with the same engine and the same 530 metric horsepower (523 hp / 390 kW) was sprinting faster despite weighing more. BMW acknowledged the issue and gradually sent out over-the-air updates to all affected vehicles over the course of the summer.
In a test C&D conducted a few days ago, the M550i was able to hit highway speed in 3.5 seconds, proving even faster than the manufacturer rated it originally. BMW explained that the issue was in the traction control system dropping boost pressure in the 4.4-liter twin-turbo V8 due to a miscommunication between electronic systems. As a result, the car tried to stabilize itself and slow down during rapid acceleration despite no apparent risks.
The problem is now considered solved, and a similar update has recently been rolled out for the 540i xDrive as well.