California regulators voted to mandate major automakers substantially increase the numbers of electric, plug-in hybrid and hydrogen fuel cell-powered models in their fleets in the coming years, eventually accounting for 15.4 percent of all vehicles sold in the state by 2025.

According to Automotive News, the new standard is part of a broader package of regulations to cut vehicle tailpipe emissions and greenhouse cases and could mean 1.4 million electric, fuel cell and plug-in hybrid cars on California freeways by 2025. That will make for some congested carpool lanes. It’s said to reduce tailpipe emissions 75 percent by 2025 and greenhouse gases 34 percent between 2015 and 2025.

This would seem to be an optimistic goal, given the lukewarm sales of standard hybrids, even with gasoline at its current inflated per-gallon prices. Pure electric cars and plug-in hybrids are just now testing the waters in limited numbers and are yet to be ready for prime time. As it is we’d guess the daily commute of the average southern California car owner would sorely test an electric car’s range. And mainstream hydrogen cars are still the 20 years away they’ve been for, well, the last 20 years.

Still, Automotive News says the measure is supported by major automakers, and we wouldn’t be surprised if it includes some kind of financial incentives when implemented to ensure all those clean-buring cars don’t sit unsold on dealers’ lots. Automakers affected by the new rule would include BMW, Chrysler, General Motors, Daimler, Ford, Honda, Hyundai, Kia, Mazda, Toyota and Volkswagen.

What’s more, ten other states that already follow California’s current auto-emissions regulations, including New York and New Jersey, could adopt similar mandates.

We’d like to think this is just the jump-start the industry needs to spark further development of electric and fuel cell-powered cars and build an infrastructure of quick-charging stations and hydrogen pumps across the U.S. Or it could be yet another speed bump in the road paved by well-intentioned legislators who otherwise feel it necessary to mandate car buyers’ choices.