Let’s see what’s the problem.

Payback has much more cars than in Underground which means much more focus needs to be put on the customization on every car, but if they do that people will complain that there aren’t many new cars. So there’s a lose lose situation here. Put more time on modeling new parts for each and every car and have less car models, or the opposite?

These many new parts needs to adapt to every part in the game like the fenders, which they’ve mostly done with this game. Underground didn’t have to do that since it was just bumper and side skirts that are customizable. The problems people had are that you couldn’t put on a liberty walk fender if you didn’t have a liberty walk front bumper for example. Now they have to adapt the front bumper to every new front fender part. Then we have the rear bumper, canards, exhausts and side skirts.

And when they’ve done that they need to model the damage for that part without causing any ugly bugs and clipping, compared to Underground just having textures as a damage model (paint scratches).