Download ZaZ Tools and GPxPatch.
Install GP4 and then patch it using the ZaZ Tools patchdownloader (it's on the Start Menu).
Run the game, calibrate your graphics, sound and controller and run a race to make sure everything is ready.
Make sure you set your graphics manually (Options -> Graphics -> Advanced) to high res car textures (this is probably why you were getting white cars before).
Download a 2010 CSM mod (I recommend josekast's over at
GP4 Forever). Or if you want to create your own just download an empty CSM mod and you'll find plenty of 2010 downloads in my sig.
=====================================================
Intel NUC 8i3, 8GB RAM, MS Sidewinder Wheel