| I own and drive both..and have for many years. They are apples and oranges in my view..but only as to performance. Maintenance has run just about the same for both cars (within a grand over three years)...typical E39 stuff. Now I would tell someone considering an E39 M5 that you will put clutches in your Beast every 40K or so....but that is a consumable to a Beast owner and not maintenance; you will get twice that much life out of 540i-6 clutch..same unit but the torque of the M eats it alive. As to others commenting that aftermarket springs, shocks and monoballs on a 540 make it handle better than a stock M, I think track experience will tell you that in truth it takes a coilover setup to make a difference that most of us amateurs could ever discern..but that is just my opinion. Monoballs are not necessary if you have fresh bushings at least on an M unless you are running a big brake kit...and that setup does benefit from monoballs to stop shimmy. I really respect the restraint of the gentleman that commented that although he could afford an E60 M car, he makes the practical choice to drive a ten year old supercharged car instead...I could not, and have not, exercised that type of fiscal restraint given the choice...ever. | 
