Do not know for sure but if you have a title should not be a problem. You cannot 'import' something like that easily but, unless it's a rusted hulk and looks complete probably no questions. Importing means you want a Mexican title. In the free zone you don't need a car permit either. People tow vehicles down here all the time. I would not tell the Mex officials that you plan on restoring it, just driving it. Talking about restoration might cause some confusion !!
What kind of car you got in mind? I restored cars for 20 years. Mostly British stuff, Triumph, Morgan, Morris, Jag. Sold some into Europe. Did a numbr of nut and bolt restorations, every thing was removed from the vehicle and built back up again with new parts. Son did a 55 TR2 from a rusted hulk and sold it for over $30K for college money. Tried to attach a photo of the 36 Morgan Three Wheeler I used to own but no cigar.
The humidity down here is not friendly to old steel. I sold everything before moving down here. Most useful thing I had for restorations was a bead blast cabinet.
