Progress must be coming at a much faster pace than we thought: Conventional gasoline engines will power only a minority of the new cars sold just two years hence, according to a new report.

That means more than half the vehicles sold will have hybrid, diesel, natural gas, or plug-in electric powertrains, right?

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Stunning.

Except that's actually not quite what the report, Automotive Fuel Efficiency Technologies (via The Car Connection), actually says.

2012 Chevrolet Sonic LTZ with 1.4-liter turbocharged engine

2012 Chevrolet Sonic LTZ with 1.4-liter turbocharged engine

A gasoline engine stops being "conventional," in Navigant's eyes, if it acquires a start-stop system. Or a turbocharger. Or any one of a number of other technologies aimed at improving efficiency and reducing fuel use.

Start-stop systems are in the process of sweeping through new cars sold in Europe and Asia, and they're now showing up on increasing numbers of new cars in North America as well.

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And turbochargers, once restricted to expensive performance cars, are now standard on many low-end Chevrolet and Ford vehicles, to name just a few.

It's all toward the goal of meeting lower and lower carbon-emission rules in the world's largest car markets (or higher and higher gas mileage, as it's termed in North America).

Thus far, as it turns out, automakers have been doing just fine in meeting the EPA's rising fuel-economy averages--mostly using technologies that don't include expensive hybrids or plug-in electric powertrains.

2011 Ford F-150 EcoBoost burnout

2011 Ford F-150 EcoBoost burnout

Instead, turbocharging, gasoline direct injection, multi-speed transmissions (rising from six to as many as 10 gears in an automatic, for instance), lightweighting, and aerodynamic improvements to reduce drag get the credit.

At least one California electric-car fan has a bet with this site that by 2020, the various alternative technologies--largely hybrids, diesels, and plug-in electrics--will outnumber gasoline cars sold in the U.S. in 2020.

Unfortunately, this report isn't proof that we're headed in that direction.

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