Magnesium burns too well for my liking. I seem to recall what might have been an F1 car way back that couldn't be extinguished once it got going.
On a related matter somebody told me (on here?) that when the fire brigade put their car fire out with only underbonnet damage, the insurance wouldn't pay because it was deemed a 'mechanical fault'. The assessor advised the owner that if he'd let it burn out completely, they would have paid for the total loss.
