A better idea (Score 1)

Instead of keeping a static limit on speed there should be a wireless system for each area that broadcasts a constant signal for speed limits and associated area code. This could be accomplished with existing telecom infrastructure already in place (WiFi, WiMax, Mobile network). The vehicle need only be aware of its current location using GPS, from which it can determine the area code and match that with the wireless reception. An automated speed governor would be more effective that way. This sort of system would be useful not only for teens but overspeeding adults, for eg. those already indicted in traffic violations as a mandatory requirement from traffic courts.