It seems that since I use DX10 I have no more AI cars. I seem to remember reading about this earlier on but I can't find the post anymore. Anyone knows what's happening and how I can get my cars back?

Well I know it happened to me too initially (after installing latest DX10 fix, cars were gone). Now it happens occasionally and I havent found any reason yet.

The Fixer has no impact nor contact with ground vehicles, unless there's a specific patch addressing them, or unless a particular scenery supplies it's own cars. I do believe that you will find a 'vehicles_land.bgl' in (FSX_root)\Scenery\Global\scenery\. Did you check the fsx.cfg, under [Main]  SimObjectPaths.2=SimObjects\GroundVehicles. Just throwing out ideas here....

 

For those long-time simmers who remeber the Flightzone Rhode Island and Portland sceneries - they had their own cars before FS did. Is this the case here, maybe?