I often get threats of my car being impounded. It's often just a hastle. I can't say they won't do it, but the only time I've actually had my car impounded was when I parked in a spot others were parking in and mine got towed. Heh.
I've driven many times to Paraguay and back, crossed the border, went through routine checkpoints, even got a ticket for speeding once, issued from the checkpoint (oops, don't want to talk about that one).
I've always used my Texas driver's license and have never had a comment.
I know it is required to get one, and I should...but I HATE tramite.
BTW - I bought my car before I had residency, by almost three years. I used to travel acorss the border with Paraguay with just my passport, insurance papers, license and cedula verde (the car's in my name) no problem.
But once, I drove up and showed my temporary residency papers. Big mistake. The law wouldn't allow me to cross the border with my car unless I had a DNI since I was a resident and the precaria wasn't good enough.
This was in Clorinda. I spent a few terrible hours there trying to figure out what to do after a 15 hour drive and no entry possible. After awhile a nice immigrations officer told me about the ferry 25 klicks down the road and that they might have pity on me. I drove down there and sure enough, with a bit of pleading and cajoling, I got them to let me cross.
When I got back I started pushing real hard to get my DNI delivered...