TIJUANA , Mexico ( CNN ) -- More Americans , tired of skyrocketing gas prices , are crossing the border to Mexico , where fueling up costs a great deal less . But the AAA Auto Club warns the short-term savings could spiral into long-term expenses . Right now a gallon of gas costs about $ 3.10 in Tijuana , while it 's about $ 4.60 just north of the border in the United States . That 's a $ 30 savings on a 20-gallon fill-up . It 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 does n't mind waiting in line -- both coming and going . `` Right now the traffic is not bad to go back , '' Fernandez said . `` It takes me about an hour , hour and a half . '' While it sounds like a big hassle , Fernandez said he just makes a shopping day out of it . `` I can come shopping ... get some groceries and stuff like that , '' he said . `` It 's like saving double . '' Watch Americans buying gas in Mexico » . The story is a similar one for Pedro Hernandez who lives in Santa Ana , California , about 100 miles to the north . He does n't make a special trip just to gas up , but he wo n't pass up a deal either . `` We can come down to visit relatives and shop around , '' he said . `` While we 're here , might as well fill up the gas . '' Hernandez saved about $ 40 on his tank . But the savings might come at a cost : Mexican gas is made with a different formula -- containing more sulfur -- which could hurt your car in the long run , according to Stephen Mazor with AAA 's Automotive Research Center . That fuel mixture can ruin the emission control equipment on American cars and cause them to fail emissions tests . `` Then ( you ) have to spend a lot of money to repair your car because of the effects of that gas , '' he said . Fernandez said his truck is running fine on the Mexican gas , for now , which is all he can afford to worry about until U.S. gas prices go down .
A gallon of gas costs about $ 2 in Tijuana ; it costs $ 1 north of the border . AAA Auto Parts said short - term costs could spiral into long - term expenses . Mexican gas contains more sulfur -- which could hurt U.S. cars .