The California Plug-in Electric Vehicle Collaborative said 102,440 plug-ins were registered in the state during that period, according to figures from the California Air Resources Board, making it one of the most advanced markets for the technology.

Drivers are offered a substantial purchase incentive to buy plug-ins in California, on top of the federal tax credit available nationwide, and are able to use the carpool lanes without having passengers in the car, which is said to dramatically reduce commuting times.