Okay, you can pretty much put any rally car in any category, so lets see how this goes
US: Ford RS200 (I love the Group B and the road version, but this Hill Climb version is too sick)
UK: Aston Martin DB9 R (Prodrive)
Japan: Toyota Celica GT-4 (two generations worth)
Germany: Porsche 959 Dakar
Europe: Lancia Stratos Safari (plus new concept Stratos bonus points)
Too many French cars, so I'm cheating and adding a new category
France: Peugeot 205 T16