Border, TIP with another person's car

[All Day]

We are going take my girlfriend's mother's car (they are both US citizens) to the border to remove the TIP and sell the car in TX. The mother is staying here in MX. Should we get some documentation before we leave, showing that we have permission to drive the car and remove the import documents?

Thanks

[RVGRINGO]

I would suggest that the daughter of the vehicle owner can drive the car without the owner present, but would also suggest a letter, in Spanish, authorizing her to do so and to remove the car from Mexico legally. Of course, she should also be added to the insurance policy as an authorized driver.

You are unrelated, so would need similar authorization; but only if you have similar INM status as the vehicle owner. If you do not have similar status, you cannot drive the car without the mother in the car.