There is no question that the MB is the better choice. The old 7 seems to be incapable of keeping its value. The recirculating ball system in my 99 S420 is so light that I wish I could retrofit it on all my cars. The trans is unbelievable, imperceptible and smooth. If you are looking for a sport car, you should look at a lighter car but the W140 is the quintessential luxury car. If I want to drive sporty, I take my 01 S600 w/ ABC definitely not the S420. As far as high speed stability, I have taken it all the way to about 120 mph and it is extremely stable and quiet with no wander and the brakes outshine the BMW. The engine in the MB is much better than the BMW because it does not suffer from as much electrical problems.