Tom Krisher Associated Press DETROIT - General Motors Corp. is evaluating future rear-wheel-drive large cars and may cancel some of them if the federal government goes through with stricter fuel economy or pollution regulations. The company hasn't stopped developing the new models and intends to proceed with the new Chevrolet Camaro and Pontiac G8 sedan, but other models that haven't been announced yet are on the bubble and may be affected by changes in fuel economy regulations, company spokesman Chris Preuss said Thursday. "If we did have a shift in the regulations, there's no question those programs would be impacted," Preuss said. Advertisement The possible changes, described earlier this week by GM Vice Chairman Bob Lutz in an interview with the Chicago Tribune, would come because rear-wheel-drive cars generally are larger, heavier and use more gasoline than smaller front-drive cars. "We've pushed the pause button. It's no longer full-speed ahead," Lutz told the Tribune. President Bush wants to reduce gasoline consumption 20 percent by 2017. To reach that number, he has proposed raising the Corporate Average Fuel Economy standard from the current 27.5 miles per gallon by 4 percent per year. The increases would begin for passenger cars with the 2010 model year and for trucks with the 2012 model year. Bush's regulations would take into account the vehicle's attributes, such as its size, instead of the current calculation based on the manufacturers' fleet. Under his proposal, the CAFE standard for domestic cars would rise to nearly 34 miles per gallon by 2015. In addition, the U.S. Supreme Court recently ruled that carbon emissions can be regulated under the Clean Air Act. Automakers have said the technology might not be available to achieve as much of an increase as Bush has proposed.