Cars now travel an average of about 15,000 miles a year. A vehicle in a ride-sharing service could go as many as 80,000 and would need to be replaced -- or perhaps refurbished in some fashion -- far more often, he said. New Revenue Source: Lyft That's why GM has invested in Lyft Inc. and is renting cars to Lyft drivers -- especially vehicles customers leased and brought back to dealers. This provides GM with another new source of revenue and keeps low-mileage models from going to the used-car market and undercutting its new-car prices. Still, ride sharing could prove to be the weak link in GM's growth strategy. Lyft is expanding but is far outflanked by market leader Uber, newly flush with an investment from Chinese ride-share company Didi Chuxing. Ammann wouldn't say whether GM would work with Uber by providing it with leased vehicles, as Toyota Motor Corp. has agreed to do, or by jointly developing a fleet of self-driving cars. Right now, he said, the company is working on this with Lyft.