Those new green stickers in the Golden State haven't exactly been golden.

A California Department of Motor Vehicles (DMV) program that distributes special high-occupancy-vehicle-lane (HOV) stickers to owners of vehicles like the Chevrolet Volt and Toyota Prius Plug-in has started slower than expected, as few plug-in drivers have taken up the state's offer to let them drive solo in HOV lanes, the North County Times reports.

California has distributed fewer than 4,000 stickers during the first seven months of the year, or about 500 a month, the DMV says. By comparison, when the state was still distributing the yellow hybrid-driver stickers, which allowed drivers of cars like the standard Prius to use the HOV lanes by themselves, it found around 2,000 takers a month between 2004 and 2007. The green sticker program, which has a limit of 40,000, expires Jan. 1, 2015.

Through July, General Motors sold 10,666 Chevy Volts in the U.S., while Toyota moved 4,123 Prius Plug-ins.