This would equally apply to other counties too, but there is a scam going on and has recently happened in a Coventry supermarket car park whereby someone - usually a woman - either comes up to tap on your window or stops you when you get out of your car and gives you a tale of woe and is embarrassed because she has run out of petrol, has no money and asks if you could you give her £2 or £3 so she can get some. Don't believe the tale for a minute and to support that this url says pretty much the same:

http://www.gazette-news.co.uk/news/4509074.Don_t_fall_for_car_park_scam/