Biggest thing they have in common is, the engine hangs out the back
Fiat Abarths (generally 500, 600, 850 + the 126 if you so choose to make your own)
Renault (specifically the R8 gordini models, again been in Retro cars)
Simca (the sport/rallye models in Retrocars)
Skoda (the S100/110/1000, the S105-130 Estelles, and the S120-136 Rapids)
VW (Type 1-4)
Hillman (Imps and all the other rootes group derivatives)
NSU (think the RO80 was a rear engined rotary wasn't it).
Maybe it is about time somone made a club for fans and owners of all marques that made the rear engine work in motorsport, or on the track for fun and performance?
Maybe call it something like RSendout (Rear Sport, the rest is obvious).
I'm sure that we could all get along, safe in the knowledge that we favour cars with the engine at the right end, and leave our brand loyalty and bigotry to friendly banter and competition at track days?
Porker (the 912 and (mid engined) 914-914/6 as much as the 911, the Speedster and the Spyder).
Could be fun. just need to get rear engined again.