BMW 635CSi (E24 Shark Nose):

 

This model was one of my favourite shapes and would be absolutely awesome with a modern “M” engine and associated running gear installed. My thoughts were an E90/2 M3 V8 or the even newer 135/140i straight six turbo with 6 speed manual gearbox. 400-500bhp is easily and reliably achieved. I like the manual gearbox in these older cars as it suits the style and driver involvement in my view. However, it is equally possible to build with the BMW paddle shift gearbox from the donor vehicle.

 

Completely updated with modern suspension, brakes, ABS, Air Con, Sat Nav / Hi-Fi etc. The interior would combine modern gauges, switchgear and technology with retro style dash, door panels and seats. Again, I may build this on a speculative basis but I welcome calls from interested parties who may wish to spec such a vehicle from the start.