That makes financial sense to commuter Ricardo Fernandez, who lives a few miles away in San Isidro, California. He makes the international run once a week during off hours and doesn't mind waiting in line to drive into Mexico and back into the United States.
"Right now the traffic is not bad. It takes me about an hour, an hour-and-a-half," said Ricardo Fernandez from San Isidro.
That may sound like a big hassle, but Fernandez says he just makes a shopping day out of it.
"I come shopping to get groceries, so the savings is double," explains Fernandez.
That's a similar story for Pedro Hernandez, who lives in Santa Ana, California, about 100 miles north. He doesn't make a special trip to gas up, but he won't pass up a deal.
"We've come down to visit relatives and shop around. While we're here, we might as well fill up," said Hernandez.
Stephen Mazor with the AAA Automotive Research Center says Mexican gas is made with a different formula which contains more sulfur. Over time, that could actually hurt your car.
"The emission control equipment, the catalytic converters, the fuel injection systems and the sensors on your newer car - or any car - really makes it a polluter, and can make you even fail a smog inspection," said Mazor. "Then you have to spend a lot of money to repair your car because of the effects of that gas."
But Fernandez says his truck is running fine -- for now. He says making ends meet right now is really all he can afford to worry about.
The extra demand from across the border is leading to shortages - and short tempers - at Mexican gas stations, some of which are starting to ration fuel.