Let's say you want to have your cars all share parts (engine, suspension bits, etc) so that you can have one generally consistent parts pile, and you of course want to have a variety of vehicles, maybe a race car, a fun commuter, a more practical commuter, a highway cruiser. What would be a good choice for this sort of thing? Examples I can come up with:
Common part: Toyota 4ag engine, some brakes and suspension bits
Vehicles: AW11 MR2, AE86 Corolla, FX16 Corolla.
Common part: Nissan SR20 engine
Vehicles: Sentra SE-R, NX2000, G20, commonly swapped s13 and s14 240sx
Common part: Ford 2.3 Lima engine
Vehicles: XR4Ti, Ranger, Mustang, TurboCoupe
Common part: Toyota ZZ engine, transmission
Vehicles: Matrix, MR2 Spyder, Celica GTS, Corolla S
Common part: Nissan VQ35 engine
Vehicles: 350Z, G35, Pathfinder, Maxima, FX35, Murano, Quest (holy crap that's a lot of vehicles!)
Common part: E36 chassis
Vehicles: e36 coupe/sedan/compact, Z3, M3
What genius cross compatible things can GRM come up with for a fleet of vehicles with common parts?