I have a 2006 M6 which is a great car except: The engine vibrates like it is out of balance on anything over about 30% throttle. On decel or out of gear, it is smooth as can be. But put it in gear and get into the throttle and at about 3200 it shakes like it has the wrong pistons in it. You feel it in the shifter and the clutch pedal. It has to be a significant imbalance in the combustion or cylinder loading to shake like it does. The local dealer's best heavy mechanic has an auto and says his is much smoother, but that does not even come close to answering the question. I love the car and want to solve the problem and would prefer to keep the local mechanics out of it. Hey, what could be more fun that a car that we have to test at WOT? I'm looking for serious suggestions on how to solve the problem. Again, it is not static balance or it would vibrate the same irrespective of throttle position. I drove blown gas hydros for many years, so I'm not expecting a Lexus shifter. Something is wrong!