Chris Woodyard

USA TODAY

Ford is putting a solar panel on the roof of its C-Max crossover

The concept will be shown at the Consumer Electronics Show

Ford says the panel focuses sunlight to charge the car%27s batteries

Ford is going to show a concept version of its electric plug-in hybrid C-Max crossover at the Consumer Electronics Show in Las Vegas that comes with a giant solar panel on the roof.

As a result, Ford says the C-Max Solar Energi Concept can get the same performance from collecting a day's worth of sunlight as from plugging in its regular C-Max Energi into a socket. The automaker estimates that the sun could power 75% of a typical drivers' trips in the concept.

The C-Max Solar Energi Concept is a "vehicle that takes a day's worth of sunlight to deliver the same performance as the conventional C-Max Energi plug-in hybrid," Ford says in a statement.

The current plug-in on sale, the Ford C-Max Energi, is rated at 108 miles per gallon equivalent, or MPGe, in the city and 92

MPGe highway, for a combined 100 MPGe. Ford doesn't estimate what kind of numbers that its solar concept would post.

It sounds like something of a breakthrough. Other automakers have put solar cells on the roofs of their cars, but didn't get much power out of them. Fisker, the defunct automaker, put an array on the roof of its Karma sedan, but officials estimated it would good only for about five extra miles a week. Toyota offers a solar option on Prius, but its usefulness is limited to powering an interior fan.

Ford says the concept has a "special solar concentrator lens similar to a magnifying glass" that makes its solar panel more effective. Since it's only a concept car, it's hard to know just how special this solar collector might be. But if it worked as billed, it would be a huge benefit for motorists who want to unplug from the electrical grid entirely.