Kevin Bullis:

Efficient engine: This modified Volkswagen diesel engine runs mostly on natural gas.

If electric vehicles don’t take off, maybe we can achieve fuel economy targets with cars that combine a little bit of everything.

Researchers at the Swiss Federal Institute of Technology in Zurich have developed an ultra-efficient new engine that runs on a combination of natural gas and diesel. When combined with a battery and electric motor to make a hybrid vehicle, it could allow a car to get the equivalent of 80 miles per gallon, the researchers say. That’s far better than the 50 miles per gallon you can expect from the most efficient existing hybrids such as the Toyota Prius. The only catch would be finding both natural gas and diesel for refueling.

In theory, the technology could provide an alternative to electric vehicles and plug-in hybrids for achieving strict fuel economy standards around the world. In Europe, the standards require cars to achieve the equivalent of 55 miles per gallon, on average, by 2020. In the U.S., vehicle fleets need to hit that target by 2025. Doing so will inevitably require automakers to sell some vehicles that surpass those targets to offset emissions from SUVs and other larger vehicles.