I have rather large speed bumps at work and my Toyota Supra would touch the top of the bumps, but my M5 doesn't touch even with 5 people in the car. You hopefully will have no problem. If you do I stonglt suggest a new driveway!
I was worried about that too, 'cause my driveway pitches down sharply toward the road and I recently installed a Belgian block apron to make matters worse. I haven't had any problem with the M5, even though my old Nissan Maxima SE used to leave a bit of its underbelly on the gravel from time to time. Not that I always remember, but it helps if you pull straight out/in rather than try to turn too sharply as you exit/enter.