Some clasic american V8 (Ford Mustang, Dodge Charger,...)
RB4 is good. Its looks like Supra with 4*4 from Impreza but slower. I like 4 door sedans with 4*4 (impreza, lancer,..) 0-100kph 4.5sec, 250kph, 2.0 turbo.
Or stronger (cup) version of RB4. This can looks like this: Wide and powerful.
Race trucks - This can be interesting racing. They have limited top speed (150kph) and very fast acceleration.
Truck like team buggyra can be very interesting.
Buggyra:
Race with trucks: