New R4 Car - Think Tank

[Mirek]

I had a look at http://www.rallycarsforsale.net/ (search “s2000”) and the price of S2000 cars is between 115 000 – 165 000 €.

S2000 are very cheap now but around 2010-2011 the top cars cost around 300 thousand Euro simply because there was nothing better available.

Afaik RGT rules don’t need any manufacturer involvement.

The way how it's done with RGT is impossible for cars built in big numbers. Imagine how many people would have to be hired by FIA to make a "mini-homologation" for every single car? The way for me is to homologate only properties (and only the "better" limit) to allow free choice of suppliers.

How suitable would something like a VW Golf R, Audi S3, BMW 1-Series X-Drive or Merc A-Class 4Matic be for R4-type regs? I know these cars are unlikely to materialise but they are the closest current-day thing to a Delta Integrale, Escort Cosworth, Mitsubishi Evo etc.

Not very suitable. None of the cars You mentioned has central differential. They all use part-time 4WD transmission using Haldex clutch or similar systems. I don't think those can be used with success in rallying. At least not before the Evos and STIs disappear.