There is enough excitement over new ideas for alternative fuel technology to make concepts like the Volt noteworthy for discussion. There are also lightweight body construction features that could be incorporated into other vehicles, as new government corporate average fuel economy (CAFE) regulations tighten.

Operating system

The Volt concept vehicle has a unique operating system (see Figure 2). For propulsion, the Volt is equipped with an electric motor that generates 160 horsepower and is capable of traveling up to 40 miles on electricity alone. The electrical power comes from lithium-ion batteries located beneath the floor of the vehicle. The Volt is also equipped with a 1.0 liter, three-cylinder, internal combustion engine.

While current hybrid vehicles use a battery-powered electric motor to supplement an internal combustion engine for propulsion, the Volt is driven on electric power only. When the lithium-ion batteries run below a 30% state of charge during vehicle operation, the internal combustion engine will start automatically, not to propel the vehicle, but to provide energy to an onboard generator that produces electricity.

Figure 1. The Chevrolet Volt concept vehicle at the 2007 Chicago Auto Show.	Figure 2. The operating system of the Volt concept vehicle features an electric motor and a range-extending internal combustion engine.	Figure 3. The plug-in charging ports for the lithium-ion batteries are located between the front doors and front wheels.	Figure 4. The unique shouldered side glass design creates a dual beltline appearance on the Volt concept vehicle.

The electricity generated is used to power the electric motor for vehicle operation, and to recharge the lithium-ion batteries. The internal combustion engine operates at a constant speed and automatically shuts down when the batteries are recharged to 80% capacity.

To fully recharge the lithium-ion batteries, the vehicle can be plugged into a 110-volt, 15-amp electrical outlet. The batteries fully recharge in about six hours. For convenience, there are two charging ports, one on either side of the vehicle between the front door and front wheel (see Figure 3).

The Volt also has a quick-charge capability. If there is not enough time to leave the vehicle plugged in to fully recharge, or there is no access to an outlet, the batteries can be recharged while the engine is running with the transmission in park.

GM says that the plug-in Volt is different than any previous electric vehicle, because of its rechargeable electric drive system and range-extending internal combustion engine. According to GM, with its 12-gallon fuel tank, this vehicle is capable of traveling up to 640 miles without a fuel fill-up or a battery recharge.

The Volt’s range-extending internal combustion engine uses GM’s E-Flex Propulsion System technology. With the E-Flex system, the internal combustion engine can be configured to run on gasoline, E85, or biodiesel.