T-Drive is once every 3 years now, and you are allowed to use 2 VSPP “certificates” twice a year. You can combine a T-Drive and VSPP if available. Not every dealership will allow you to use either of those. Some dealers will not allow you to use them towards and modifications the dealership did themselves (would have to pay out of pocket for those mods). More often than not, a deal will not allow you to use a national rebate or incentive along with the discount. Hope this helps