My dream car had always been the M5...until I test drove the 540i. It understeers like a cow on skates. Now I'm leaning towards the M3 for my next car. Like S38, my priority is on having fun at the track (and on twisties and at autocrosses), and the lighter car wins hands down. Of course, if my priorities leaned towards transporting the family around in comfort, I'd go for the M5.