i think you should only be able to modify japanese cars but with real aftermarket parts such as the modification on the fast and furious tokyo drift game. pretty hard to make a car look rice in that. so things like body kits from top secret, veilside, bomex, vertex, origin, chargespeed and bizz, and stuff like when you upgrade the intercooler you can see a different one in you front bar as you upgrade, and your exhaust changes when you upgrade it etc car lowers when you put better suspension parts in it and so on.
because its only really the european car enthusiasts that want to keep a car standard.
and what they dont get is everything we do to our cars influences on our personality,
in real life when you have a modified japanese car its more than just making it go faster or making it wider lower or even making the suspension stiffer, its a passion, its a lifestyle, its a drug once you put that first boost controller on your car your hooked