Toyota and General Motors are neck-and-neck in the race to put a plug-in hybrid in your driveway, but they’re recycling an idea GM explored almost 40 years ago and tossed aside like a depleted battery.

The concept car with the cumbersome designation XP-883 was nothing more than an experiment relegated to history, but it worked a lot like the Toyota Prius and Saturn Vue plug-in hybrids the two companies are working on today. It was sufficiently ahead of its time for Popular Science to call it "radical" and ask, "wouldn’t it be great to have a car that changed from electric drive for use around town to gasoline power for highway driving?"

"It makes so much sense," the magazine wrote in July, 1969, "that we feel they’re missing a bet if they don’t put it in production."

The XP-883 looked like an Avanti hatchback or the AMC Gremlin‘s prettier sister. At 122.2-inches long, 57.3-inches wide and 46.3-inches high, it was a little bigger than a Smart ForTwo and a little smaller than a Honda CRX. It had a fiberglass body for light weight, but just what it weighed has been lost to history.

The heart of the car was a 35 cubic inch (573 cc) two-cylinder engine — small enough to be exempt from the emissions rules of the day — coupled with a DC motor powered by six lead-acid batteries just like the one under your hood. You could tool around in all-electric mode or in gas-electric mode, according to PopSci. In hybrid mode, the electric motor did all the work to about 10 mph, at which point the gasoline engine took over. If you needed to really get up and go, the engine and motor worked in tandem. Still, the car was as slow as it was advanced. Top speed was just 60 mph, and it needed 28 seconds to get there — making it only slightly faster than a Citroen 2CV6.

The series-wound motor was placed coaxially with the front drive shafts and drove them through a planetary reduction gear and a differential. The engine was mounted ahead of the motor. The batteries were mounted under the cargo area between the rear wheels, just like modern-day hybrids. A flywheel alternator kept them charged, and there was an onboard charger you could plug into a 115-volt socket to top them off at home. "You may think this little hybrid is pretty far advanced," PopSci wrote, "but the fact is it could be built today. It’s not held up because the engineers are searching for a breakthrough."

So what’s taken so long?

Photos copyright GM Corp. Used with permission, GM Design.