New installation / ferrari look like jaguar

no you don't need to do it. If you play gp4 without csm, you can open teameditor and then go to the tab carshapes. There you can activate Force best carshapes ( Use Lod0 only) and after this, export it to gp4. Now you can play with only lod0 of the cars

The cars.wad will only get larger by using big textures, it can be more than 1 GB big maybe. It's very important to rename all five lods per car or all ten lods per team. I remember a few weeks ago I did a mistake when renaming lod 2 of car 2, and there were eleven cars with blinking textures then ingame. After renaming the eleven car 2 lod 2 gp4-files right and put them into the cars.wad the error was gone. So please, notice that renaming textures is one of the most important things when using other cars, especially cars which you painted on your own. Have fun!