GM's Volt misses sales target as probe continues General Motors Co.'s Chevrolet Volt missed its U.S. sales target of 10,000 cars in 2011, the company said. Chevy dealers sold 1,529 of the plug-in hybrids in December, leaving the brand 2,329 shy of its goal. A slow production ramp-up kept dealers in short supply until last month, and a federal investigation of three fires that occurred after Volt crash tests lowered demand for the car, according to Bandon, Oregon-based CNW Marketing Research Inc. U.S. dealers sold a total of 7,671 Volts last year. But December was only the third month that Chevy dealers sold the Volt in all 50 states. GM allowed dealers to sell as many as 2,300 demonstration models to retail buyers starting in late November, helping spur a 2.8 percent increase from October and the model's best month yet. Volt sales through November totaled 6,142, the company said. GM is expanding production to 60,000 Volts this year with 45,000 of them earmarked for the U.S. The Volt is being investigated by the National Highway Traffic Safety Administration because its batteries caught on fire in the weeks following three government crash tests. NHTSA announced a safety probe of the Volt Nov. 25. The Volt investigation has the potential to harm the reputation of electrified vehicles. Lithium-ion batteries, such as those used in the Volt, are also installed in all-electric cars, such as Nissan Motor Co.'s Leaf and models made by Tesla Motors Inc. A Volt caught fire three weeks after a May 12 side-impact crash test while parked at a NHTSA testing center in Wisconsin, leading regulators to conduct more tests. The Volt can go about 40 miles on electricity before its gasoline engine kicks in and powers a generator to recharge the battery. The car has a range of 379 miles with electric and gasoline power combined. The Volt's battery can also be recharged at an electrical outlet. The U.S. Environmental Protection Agency estimated the Volt would average 60 miles per gallon in combined gasoline-electric driving, compared with 50 mpg for Toyota Motor Corp.'s Prius. Volt's range is about four times what Nissan's Leaf travels on a single charge. GM is trying to reassure customers. North America President Mark Reuss sent a letter to Volt owners on Nov. 28 saying that if they have concerns about their safety, the Detroit-based company will provide them with another model as a loaner until the U.S. investigation concludes. GM also is willing to buy back Volts from any owners who are concerned for their safety. The Volt was the highest-ranked car in Consumer Reports' owner-satisfaction survey, taken before the U.S. probe was announced. The magazine said 93 percent of Volt owners who responded said they would buy the car again. The plug-in hybrid finished ahead of the Dodge Challenger and Porsche 911 sports cars, each of which had 91 percent owner-satisfaction scores.