Most radios used for R/C cars are 2-channel: direction and speed. There are also 3-channel radios; the third channel is used for fancy stuff. For example, some people wire up lights on their car to the third channel. Higher number of channels (up to 8) is intended for aircraft, but can it be used for cars? This will work, but there are a few things you must keep in mind. Different radios are designed for different applications. You might have to use some trial and error to figure out which channel you want to use for the throttle and which for the steering on your car. Also, multi-channel radios are intended for airplanes and other flying R/C models. The throttle for a car radio is spring loaded, but for an airplane it is not. This means that on a car radio when you let go of the throttle, it will return to the neutral position. On an airplane radio the throttle will stay, by design, wherever you had pushed it to. It will require some getting used to, but it can be done. Yes, there are also legal issues as well! You must use the correct frequency for your radio. Certain frequencies are reserved for air use only, and some others are for ground use only. At the end of this document, see "Legal frequency - channel tables", there is a list of legal frequencies for ground vehicles only.I personally am no lawyer, and as such I am not familiar with all the legal subtleties! In North America the government authority responsible for this is the FCC - Federal Communication Commission - which controls everything transmitted trough the air. They have a web site, and the relevant pages can be found at: <http://www.fcc.gov/wtb/prs/radcntrl.html >, and <http://www.access.gpo.gov/nara/cfr/waisidx_00/47cfrv5_00.html > In the UK it is The Radiocommunications Agency; here is the best link I have been able to find: <http://www.radio.gov.uk/publication/ra_info/ra60.htm >. Good luck!