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2009 Z4 Break-In Issue


I just bought a 2009 BMW Z4 sDrive35i. The manual states that the break-in period for the car is 1,200 miles and I’m not supposed to go over 100 mph and 4,500 rpm during this period.

Well, I was on the freeway varying speeds from 55 to 65 mph when I tried to overtake this slow car next to me to change lane. When I stepped on the gas(did not floor it), all of a sudden the rpm shot to 5,500 rpm, but the car did not accelerate. I suddenly stepped off the pedal and the engine hung for a second at 5,500 rpm then went down in rpm. I was at 690 miles into the break-in period when this happened.

Did I ruin my engine by going over the 4,500 limit this one time? If so, how can I tell? Or am I just worrying too much?

One time didn’t hurt the engine. They just don’t want you doing it regularly.

It sounds like you have a different problem, though. A BMW at 5,500 RPM should accelerate like crazy. The way you describe it, the transmission was slipping, which is a serious issue that should be checked out. Is this a manual or automatic transmission?

You did not hurt the engine, but I wonder why the car didn’t accelerate at 5,500 RPM. I would have expected the car to be pulling very hard at 5,500 RPM.

I’m going to assume this car has an automatic transmission, and it downshifted to pass, but when you took your foot off the gas it hesitated and then shifted back to a higher gear.

I suggest you pay more attention to the traffic and less to the tachometer. Unless you accelerate hard or drive at high speed you shouldn’t exceed the 4,500 RPM maximum (except for very brief periods) during the break-in mileage.

The transmission computer is probably programmed to limit engine speed during the break-in period, except under emergency conditions. Keep a light foot until the 1,200 miles have passed, then stomp on it to your heart’s content.

You didn’t hurt anything. Is is possible BMW has programmed the computer to limit RPM’s over the 1st 1,200 miles? Hard to understand why the car didn’t accelerate.