AVOID like the plague or COVID 19 if you can. Black box interfered with the Merc on board computer of my car and caused it to go into limp mode. Car would not accelerate above 40mph - causing many dangerous instances. Merc charged me £45 everytime they needed to remove this black box to access the OBD port which is usually free. Finally got the black box moved using a RAC engineer to the batter - only to receive email from RAC that my policy is cancelled as the black box is now not working. AVOID AVOID AVOID. RAC shoould not be fiddling with customers cars.... you will spend more in the long term and SUFFER for no fault of yours. SHAME ON YOU RAC