That's good to hear. Over a year ago there was quite the discussion on weight, and I weighed my car three times on truck scales, and came up with weights within 10 lbs. What I got on average was 4180 lbs with a full tank, stock tires/wheels and nothing else in the car. I would guess my car is the worst case since I have all the options, including a Blinder M40.
I don't know what the options weigh, but I'll bet the listed 4012 "curb weight' for the M5 is without any options. Sunroof, high end stereo, ventilated comfort seats, pdc, nav, rear side airbags, Sirius radio, heated rear seats, sunshades, and even full leather probably add the additional 170 lbs.
