Nowadays, we’re used to manufacturers under-reporting performance figures. 0-60 mph (0-96 km/h) times are perhaps a few tenths slower than what actually can be achieved, or perhaps on a dyno, a car will output the odd 70 extra horses or so. BMW is notorious for being modest with their numbers, which is why, when Car And Driver tested the 2021 M550i xDrive, they were a little surprised to find it off the pace.

Known for their extensive testing, the publication found that the car clocked in a 0 to 60 mph time of 4.1 seconds. Under normal circumstances, such a time would be considered mega quick for a four-door sedan, but BMW’s official figure stands at just 3.6 seconds.

Suspecting that their test car had been given a lower than recommended octane gas, the M550i xDrive was welcomed back for a rerun. This time the car did better but still clocked in a 0 to 60 time of 3.9 seconds — 0.3 seconds off the pace.

See: The 2021 BMW M3 Competition Makes More Power Than Advertised

A 2021 BMW M550i xDrive in Aventurin Red metallic

While 0.3 seconds may not seem anything to quibble over, Car and Driver points out that they’re usually able to beat or match BMW’s quoted figures. Plus, thanks to the combination of BMW’s tried and tested auto ‘box and all-wheel-drive, it’s reasonable to assume that the M550i xDrive’s launches were fairly idiot-proof.

The publication requested another car from a different fleet but, by then, BMW had caught wind of the issue and informed them that they would be looking into it. A few days later and BMW had found out that the problem was a miscommunication between the engine’s computer and the M550i xDrive‘s stability control module which ultimately resulted in the car’s turbocharger boost pressure dropping.

While early M550is aren’t affected, the issue impacts 2021 M550i xDrive and 2021 540i xDrive models.

BMW has since notified owners and dealerships and stated that an over-the-air software patch can be expected this summer. The patch will enable both systems to work in unison as they should and allow 2021 model year cars to hit their claimed acceleration times.