Giant Motors, an automaker partially owned by Mexican billionaire Carlos Slim, is working on a prototype electric taxi to replace the gas-guzzling cabs polluting Mexico City's air, a company executive said. Giant has partnered with electric vehicle maker Moldex, a unit of Mexican breadmaker Grupo Bimbo, and four Mexican universities to produce the environmentally friendly car that will eventually replace part of Mexico City's more than 130,000 registered cabs, said Elias Massri, chief executive of Giant Motors Latinoamerica.

"We're developing the prototypes and hope to finish them this year to find a viable solution, an electric vehicle, that genuinely replaces gasoline-using cars," Massri said in an interview.

A thick haze periodically descends on Mexico City, the Western Hemisphere's largest megalopolis, irritating eyes and throats and prompting authorities to issue health warnings and force cars off the streets. Air quality in Mexico City, home to an estimated 5.4 million vehicles, has been particularly poor in recent weeks. Slim's Grupo Financiero Inbursa has a 50 percent stake in Giant Motors. In February, Giant Motors and China's Anhui Jianghuai Automobile Group Co Ltd (JAC Motors), along with distributor Chori Co Ltd, said they would invest some $210 million to build SUVs at a plant in the central state of Hidalgo. Giant Motors and JAC aim to be producing some 10,000 vehicles per year at the Hidalgo plant within four years, said Massri. Passenger cars will account for 70 percent of total output and the remainder will be commercial trucks. Initially, the Giant Motors-JAC Motors joint venture will focus on selling to Mexico's growing domestic market, with an eye to expanding into other Latin American nations, Massri said.