My wife and I have made the trip three times in the last year. We have had no difficulties. We drove from Laredo. Traveled with a dog.
My biggest recommendation is to always top up your tank when you get to a quarter tank. It's not always easy to find a Pemex. Almost ran out of gas a couple of times. One time I had to buy some off the back of a truck at a toll station.
Other than that it's all good.