1. A vehicle guidance system comprising: a measurement system; a processor arranged to receive information from the measurement system and convert said information into at least one time-to-contact based parameter; and a control system arranged to receive the at least one time-to-contact based parameter from the processor, compare the at least one time-to-contact based parameter with at least one target time-to-contact based parameter, and use the at least one time-to-contact based parameter and the at least one target time-to-contact based parameter to automatically guide the vehicle to close a motion gap.