Because the price of the two versions of the cars is about the same, the dual system buttresses the bottom lines of automakers such as General Motors and Nissan. But it's being blamed for a surge in auto-related fatalities in Mexico, where laws require virtually no safety protections.
"We are paying for cars that are far more expensive and far less safe," said Alejandro Furas, technical director for Global New Car Assessment Program, or NCAP, a vehicle crash-test group. "Something is very wrong."
In 2011, nearly 5,000 drivers and passengers in Mexico died in accidents, a 58 percent increase since 2001, according to the latest available data from the country's transportation department. Over the same decade, the U.S. reduced the number of auto-related fatalities by 40 percent. The death rate in Mexico, when comparing fatalities with the size of the car fleet, is more than 3.5 times that of the U.S.
Nevertheless, Mexico hasn't introduced any safety proposals other than general seat belt requirements for its 22-million strong auto fleet. Even then, the laws don't mandate three-point shoulder belts necessary to secure child safety seats.
Brazil and Argentina, on the other hand, have passed laws requiring all vehicles to have dual front air bags and antilock braking systems by next year.
An Associated Press investigation this year found that Brazil's auto plants produce cars aimed at Latin American consumers that lack basic safety features. Like Brazil, Mexico doesn't run its own crash test facility to rank cars' safety before they hit the road.
Dr. Arturo Cervantes Trejo, director of the Mexican Health Ministry's National Accident Prevention Council, said the country has a long way to go to upgrade safety standards, but challenging the nation's $30 billion auto industry could be difficult.
"It's a complicated subject because of the amount of money carmakers bring to this country. The economy protects them," Cervantes told the AP. "But there are plans, there is a strategy. We have a working group with the car industry."
Auto plants cover a swath of central Mexico, cranking out about 3 million cars a year while lifting into the middle class auto hubs in the states of Aguascalientes and Puebla. In a matter of a few years, Mexico has become the world's fourth biggest auto exporter, despite having no homegrown brands, and the country's car fleet doubled between 2001 and 2011, the latest national figures show.
In fact, consumers in "first-world" countries are paying the same or even less for safer cars.
For example, basic versions of Mexico's second most popular car, the Nissan Versa, made in central Aguascalientes, come with two air bags, but without electronic stability control systems, which use sensors to activate brakes when a car loses control.
The sticker price of the newer generation of the sedan comes to $16,000. The U.S. version of the same car has six air bags in the front, on the sides and mounted in the roof, in addition to an electronic stability control system. That sticker price is about $14,000.
Similarly, the basic version of the Chevrolet Aveo, which has been revamped and renamed Sonic, sells for about $14,000 in the U.S. and comes with 10 air bags, antilock brakes and traction control. Its Mexican equivalent, the country's top-selling car, doesn't have any of those protections and costs only $400 less.
Nissan Mexicana spokesman Herman Morfin said in a statement it is "common practice" to add different features, depending on the intended market.
"Because there are many choices of specifications and equipment, specific marketing strategies by country, in addition to the tax difference among countries, states and cities, also including transportation and delivery costs, it's not possible to make a direct comparison among vehicles sold in each market, based on the list price published on the Web," Morfin said.