if the car looked mint and the engine looks like this, something is wrong.

http://cgi.ebay.com/ebaymotors/BMW-750i-850i-ENGINE-RUNNING-IN-CAR-mint-ONLY-54K-WoW_W0QQcmdZViewItemQQcategoryZ33689QQihZ007QQitem Z170209898004QQrdZ1QQsspagenameZWDVW

hmm, I would agree... although it is possible that it's just minor dusts :).

The biggest killers of older 750's are a dead transmission or an overheated engine.
Either costs more in repairs than the car is worth in mint condition otherwise.

Most 750 owners only seem to polish the outside of the car and ignore the engine compartment altogether until something quits. If you see a shiny 750 engine it either belonged to one of the few enthusiasts left or just had a good detail so the dealer can jack up the price.

So many 7s on for sale in the UK and at bargain prices.

Check out www.pistonheads.com