Many, many years ago my wife and I were driving South to my parents in Somerset. We stopped at a Motorway Services for petrol.
I had just filled up when an Austin Maxi, with two women on board, pulled in behind me - with flames visible behind the radiator grill.
I shouted at them that they were on fire and they jumped out and ran away (a long way!), leaving the doors open.
I told my wife to get into the driver's seat of our car and be prepared to get away quickly and grabbed a fire extinguisher. The guy filling up on the other side of the pump scarpered.
I popped the Maxi's bonnet and fired the extinguisher into the engine bay, then opened the bonnet fully. The coil and associated wiring on the side of the block were burning, but were soon put out. Damage was minimal and the filling station survived!
Next, the girl from the pay kiosk was at my side with a claim form, wanting me to pay for using the extinguisher!
I declined and pointed to the two dots in the far distance - "get them to pay" I said.
I paid for my fuel and left.
Its true what people say about "not getting involved" you can just land yourself in a load of trouble

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I still do it though

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Bob.