The company has moved 6,142 Volts through the first eleven months of the year. That means that the 10,000 vehicle mark could be out of reach until early 2012, said GM sales chief Don Johnson.
The Volt's main rival, the Nissan Leaf, has recorded sales of 8,720 units thus far in 2011.
After choosing to launch the Volt in just a handful of states, GM reported that the car enjoyed its best ever sales month in November (1,139 units) as availability continued to expand. The company hopes to offer the plug-in hybrid in all 50 states by the end of 2011.
Despite slower than expected Volt sales throughout this year, GM has stated in the past that it hopes to sell significantly more units in 2012.
"We are ramping production so we can hit a number on the order of 45,000 for next year,"ť GM CEO Dan Akerson told CNBC last month.
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