Last year, my son arrived in his car with the doors all scraped. Now I know he’s not terribly good at manoeuvring (he does, fortunately, have plenty of other qualities!). He explained that the carpark in the building where he lives is cramped and the underground passage leading to his parking space is narrow. It’s not easy parking his car under these conditions. I soon had an idea for overcoming this situation: estimating the distance each side of the car as it enters the garage space. A central unit gives a simple visual warning (illuminated indicators) if the limit distances are reached or even exceeded.