GM's entry at CES is an app for its OnStar communications system that allows owners of the upcoming Chevrolet Volt to remotely monitor and control some functions within the car. In particular, assuming it's plugged in, owners can use their phones to order the car to charge up its battery by remote control. The Volt is a plug-in hybrid car that goes on sale later this year.
The Chevy Volt is a plug-in hybrid. It's more properly called an extended-range electric vehicle, or EREV. That means that like today's hybrids, such as the Toyota Prius, the Volt has both an electric motor that runs on a battery, and a conventional gasoline-powered engine.
The key difference is, as the name suggests, a plug-in hybrid can be recharged by plugging it into ordinary household current. The battery in a hybrid like the Toyota Prius can't be plugged in; it gets all its energy from the onboard gasoline engine. That's less efficient and more expensive per unit of power than recharging the battery by plugging it in.
The cost-per-recharge advantage is even greater during off-peak hours, when household current is cheapest. One of the key benefits of the new remote-control app unveiled today by GM is that Chevy Volt owners can remotely order their cars to recharge themselves during off-peak hours, without having to go outside.
The second thing that sets a plug-in hybrid apart from today's hybrids is that the wheels of a plug-in hybrid are always driven by electricity. The conventional gasoline engine acts exclusively as a generator to recharge the battery. A conventional hybrid is driven sometimes by the onboard gasoline engine; sometimes by battery power; sometimes by both.
The net effect for the plug-in hybrid is much higher gas mileage, when you factor in a range on battery power alone of up to 40 miles per charge, according to GM. The battery-only range for most conventional hybrids is almost negligible in normal driving.