I am going to chime in here based on my limited but recent experience. At the Palomas crossing they checked that my name matched on my driver's license, registration and credit card. From everything that I have read here you are only allowed to temporarily import one motor vehicle here at a time. Rhode trip, if your name is on the title of both vehicles, even if your wife is riding one of them, it might appear to the Mexican officials that you are trying to import two vehicles and they will not let you do that. Furthermore, given all of the reasons that have been give here your wife will have to have her name matching on her driver's license, the vehicle registration (title not needed), and the credit card that she is paying with. On the other hand if she is carrying a notarized letter that authorizes her to take your vehicle into Mexico and her name on that letter is exactly as it is on her drivers license and the credit card of payment then maybe there is no problem. In so many of these situations it very much depends on the person you are dealing with at Banjercito and how willing they are to think outside of a very densely defined box. I have no idea how many married couples do this sort of thing but I would guess not many so they may never have seen anything like this before. Call Banjercito: 011-52-555-328-2329. They were very helpful when I called. Buena suerte.