Tesla Model S at gas station

Plug-in vehicles, battery-electric cars and plug-in hybrids are cutting US gasoline use by 45 million gallons a year, which means Americans are already saving $100 million a year in refueling costs thanks to EVs. Now, imagine how those savings might look if startups like Aptera, Coda Automotive and Fisker Automotive had created hits instead of flops.

Those numbers come from the Union of Concerned Scientists (UCS), which calculates that there are almost 200,000 plug-in vehicles on US roads, with all but about 30,000 bought within the past three years. Unsurprisingly, Californians are the most enthusiastic buyers, accounting for 46 percent of new plug-in vehicle sales. That means Golden State residents, who doubled their plug-in vehicle purchases last year, are spending $40 million less on fuel than they'd otherwise spend. Of course, plug-ins tend to cost more to purchase than their gas-only counterparts, but either way, the UCS believes these results are "encouraging."

Plug-in vehicle sales in the US last year came up just short of the 100,000-unit mark, with EV sales rising 90 percent to 99,827 vehicles. The Chevrolet Volt extended-range plug-in, Nissan Leaf and Tesla Model S battery-electric vehicles combined to account for about two-thirds of those sales, with Leaf sales doubling last year and Tesla sales jumping by a factor of eight. Despite the increases, plug-in vehicle sales can't compare to the more than 234,000 units of the four Prius variants that Toyota sold last year.