We were on Black Rock Sands a few years ago, friend of mine was charging his remote controlled car from his car 12v socket, was a bit of a hot day.
We were sat there and heard a pop noise but didn’t think anything of it and carried on chilling out.
About an hour later he went to his car and exclaimed in a very Anglo Saxon way that something was wrong.
We rushed over to find the interior of his car completely ruined, the seats were all burnt, the dash had melted all over his girlfriend’s handbag (and phone, wallet etc), all the roof lining was down, center consol a mess, but the fire had gone out.
We figured that the batteries had overheated, gone bang and burned away or awhile before it had consumed all the oxygen inside and put itself out. Car was a write-off though. Funny thing was we were sat only 10 feet away, people walking to and from the sea close by and no one noticed!