Cars will cost more, but cost less

All those technological improvements will drive up the sticker prices. The EPA estimates that the average vehicle in 2025 will cost $2,400 more than today. Over it's lifetime, though, the same vehicle will save consumers $8,200 in fuel expenses.

"You'll more than make up for the extra cost of the car," Sinnamon, of Environmental Defense Fund, said.

As the technology becomes commonplace, prices should come down. The new generation of hybrids are cheaper than the current generation, due to design innovations (that P2 system), NRDC's Hwang said. The same type of innovation in future engines is hard to predict specifically, but easy to expect.

And maintenance, too, could cost consumers less, Edmunds.com's O'Dell said. All the maintenance electric cars need, for instance, is "is to rotate tires and change window wipers," in O'Dell's words, and the more-precise and computer-controlled engineering in cars should require less maintenance overall. Though, of course, the chance of a defective part prompting a recall will always be there.

At today's gasoline prices, fueling the average new vehicle costs nearly $1,700 annually. In 2025, the fueling the average new vehicle will cost closer to $900 – 45% less. And that's assuming the price of gas stays the same. The latest Energy Information Administration Annual Energy Outlook predicts that gas prices will be 25% higher in 2025 than in 2011 – making each gallon saved that much more valuable. (It also predicted prices in 2011 would be $2.80, not $3.70, so take that prediction with a grain or two of salt.)

"This is great for consumers. They're going to benefit more than anybody," Sinnamon said. "They'll still have a broad range of vehicle size, use and style choices, but they'll have even more high-mpg options."