The Chevy Volt is what GM calls a "extended-range electric" vehicle. It carries a bank of lithium-ion batteries underneath as its primary fuel source. The batteries can be charged by plugging them in overnight, and can power the vehicle to a range of around 38 miles. Should the driver require a longer range, an on-board 1.4L 4-cylinder gasoline-powered engine automatically starts up to generate additional energy. A regenerative braking system provides additional charging whenever the vehicle slows. Overall, the Volt's miles per gallon equivalent (MPGe) is estimated at 98. The Volt also features an "EV Hold Mode." The system allows the driver to control when the electric motor is active. In doing so, the driver is able to utilize battery power when it is most effective, while driving in the city, for example. The Volt is capable of a top speed of 100 mph, making it suitable for highway driving. Like other electric cars, the Volt has lots of torque right from the get-go, making for quick starts and fun driving. However, steep hills, driving at faster speeds and flooring it at every red light will all reduce that 38-mile electric-only range. Chevrolet understands that an electric car will only be successful if drivers and passengers don't feel compromised by the experience. Safety features include eight air bags, which includes a knee bag for the driver as well as side curtains for all passengers. Standard equipment features navigation, satellite radio, Bluetooth and remote keyless entry are all standard equipment. A standard cargo cover keeps the contents of the 10.6-cubic-foot trunk hidden. GM's OnStar system is included for five years. A standard Bose sound system features a 30GB hard drive and USB port. This system uses less energy than other stereos, allowing more power to be utilized at the wheels. Leather seats are even available for a little touch of luxury. A rear camera and park-assist system are also available, as are heated front seats.