Sdog that WRX is sweet.
I like the BMW and Nissan Skyline suggestions.
I don't know how you guys feel about the 5-0, but a police car with a working light rack would be cool. Just imagine the high speed chases that could be had. An ambulance body on a monster truck chasis would be killer, but that's just me.
I have to say I am surprised RS hasn't released any emergency type vehicles yet. Those models seem to appeal to everyone.