As far as NASCAR, Ford and Chevy (notice they're the only rep of GM) have been in and out of official sponsorships many times over the years. Toyota was trying to get a foothold in the American racing scene. NASCAR is in decline right now (mostly because of reasons stated) and they feel their money is better spent elsewhere. They still have a presence in other forms of racing (NHRA, lots of road events), but there is talk of a return to NASCAR (just rumors at this point) if certain points are met... don't hold your breath.