Speeding is one of the major causes of road accidents. As drivers usually claim they exceed the speed limit unintentionally, having an in-vehicle automatic speed limit warning system could help to prevent a significant number of speeding and accidents from happening. Existing systems cannot provide consistent and satisfactory performance. In this paper we investigated automatic speed limit transmission based on RFID technologies. We conclude that both passive and active RFID systems show potential in such scenario, but are suitable for different scales of applications. For both technologies, challenges are identified and addressed, with system prototypes proposed and demonstration systems developed to prove the feasibility of our design concept
