Depends. A 135i, 5 series, 6 series, 7 series, M series, X5M or a X6M are fast but anything else are not as fast.
32m
13m
Yes, there is an iPhone power meter app for the BMW M. It is free, and promoted by BMW on their site, http://www.bmw.com/com/en/newvehicles/mseries/x5m/2009/g_meter.html. Here is the direct link to the Apple App Store: http://itunes.apple.com/us/app/m-performance-meter/id344494968?mt=8