Coasting downhill at say 50 mph and maybe 2k rpm, approaching a corner so I lightly step on the brakes, the transmission abruptly downshifts which causes engine speed to jump instantly to say 4k rpm, which results in a ton of engine braking. No real pattern as to what speed I am coasting at, it happens at almost any speed. This happens in normal steptronic mode, although I haven't tried to replicate the problem in Sport or Manual modes. I have owned a 2002 330cic and a 2005 545i both with Steptronic and put in about 100,000 miles betweent thos two, and have not experienced this problem. If you were riding in the car with me, you would respond "WTF?!" It is that noticeable!
Then, as I get back on the accelerator (normal, not hard) after entering the corner, it seems to take longer than normal for the car to upshift to the gear I would expect at that MPH and RPM.
Any idea of causes? I know that BMW claims the transmission fluid is lifetime, but I don’t believe that!
Thanks in advance!