The M550i xDrive lacked power, but now the 523bhp sedan accelerates from 0 to 100 km / h in 0.6 seconds.
The 2021 BMW M550i xDrive test earlier this year showed a slower than expected acceleration time to 100 km / h, which was 4.1 seconds. While this is better than the Ferrari F40 30 years ago, these days it is slower than the 3.9 seconds it took us to get to the 100 on the X5 M50i, which weighs 388 kg more than the M550i. At the same time, they have the same power units with a capacity of 523 hp, which caused bewilderment.
This rarely happens, but turbocharged cars sometimes run slower than expected, and low octane fuel is often the culprit, in this case 91 RON (RON) Californian gasoline. Re-testing with a freshly filled tank of RON 93 (95 RON) gasoline reduced the time to 3.9 seconds, which is still longer than BMW’s claimed 3.6 seconds.
When BMW learned of the test results, engineers went to work and found that a software glitch was causing a communication failure between the engine computer and the vehicle’s stability control module. When starting from a standstill, the stabilization system intervenes and reduces the boost pressure, preventing it from gaining full power and adding tenths of time to the speed of 100 km / h, which is a problem for all M550i and 540i xDrive models of 2021.
BMW sent out a statement this summer informing owners that a fix is pending. The update can be done over the air or by contacting your dealer’s service department. Now, a few months later, the experts tested the same version of the M550i and accelerated to 100 km / h in 3.5 seconds, and a quarter mile (402 meters) scored in 11.8 seconds at a speed of 192 km / h. It looks like all 523 horses are present and can work as expected.