Again, PSP couldn't handle those draw distances or that level of detail in the environments/car models in a million years. I think someone has rose tinted glasses of how PSP games looked...
Here's DIRT2 from PSP
Yep that all looks IDENTICAL to WRC4...
Here's some Gran Turismo for you which was over 5 years in the making with a higher budget than any 3rd party portable title would ever be granted.