Radio-controlled cars are miniature model cars or trucks that can be controlled from a distance using a specialized transmitter or remote. The term "RC" has been used to mean both "remote controlled" and "radio controlled", where "remote controlled" includes vehicles that are controlled by radio, infrared or a physical wire connection (the latter is now obsolete). Common use of "RC" today usually refers only to vehicles controlled by radio, and this article focuses on radio-controlled vehicles only.
Cars are powered by various sources. Electric models are powered by small but powerful electric motors and rechargeable nickel-cadmium, nickel metal hydride, or lithium polymer cells. There are also brushed or brushless electric motors - brushless motors are more powerful and efficient, but also much more expensive than brushed motors. Most fuel-powered models use glow plug engines, small internal combustion engines fueled by a special mixture of nitromethane, methanol, and oil (in most cases a blend of castor oil and synthetic oil). These are referred to as "nitro" cars.