If you can get the 500E, and are willing to drive it to Atlanta, I'll pay for all the gas just to ride in it!!! If your friend would seriously trade a 500E towards an 850, then I submit he is so dense that light waves bend as they pass him. My friends white 850 without doubt has the sexiest physical presence I have seen on a car in a long time, but also coined the phrases "tempermental" and "quixotic"! It spends as much time running on 6 cylinders on the way to the bimmer docs as it does on 12!
Maybe you ought not tell him my opinion - instead, tell him that the shop forums say that 500Es need complete steering rebuilds and suspension overhalls by 50k miles, and the timing chains were originally made by shimano for coaster brake bicycles! Then offer him $25k and a ride to the BMW shop.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E