Jenny Nettles drove a Midget MG which she gave to Sarah Jane Smith before leaving Earth with Kal, Sarah's car having been destroyed. (AUDIO: Kaleidoscope) It had the UK registration plate RMF 654L. (TV: Robot)
Although it was originally red, (AUDIO: Kaleidoscope) it was gold by the time of the Third Doctor's regeneration. Sarah drove the car to investigate the National Institute for Advanced Scientific Research. (TV: Robot) By 1981, she was driving a different car. (TV: A Girl's Best Friend)
Sarah was apparently driving her MG once again in 1995. (HOMEVID: Downtime)