I do have a first aid kit and fire extinguisher, but only coz coucil says I have to carry them.
First aid kit ....Im not allowed to use unless its on myself. If a customer requires the need of first aid......im allowed to offer them the use of the first aid kit.....but not administer first aid coz im not trained in first aid.
Fire extinguisher.....if my Omega caught fire......it would be a race on who could run the fastest!! 
Im not hanging about with a tank full of lpg in the boot 
I actually tried once extinguishing an under-bonnet car fire (not my car) with one of them fire extinguishers... was a pointless exercise. The fire brigade came in minutes and sprayed the car with foam, which did finally stop the fire.
Apparently you are not supposed to open the bonnet of a car with an under-bonnet fire, ‘cause you'll be flaming the fire with fresh air supply, instead you should just pop the bonnet and use the extinguisher through a crack. Ridicules... the spray only last for a few second, and then you can't see where's the fire so spraying it in the general direction of the engine block has no effect... In this case a fuel line ruptured and the petrol caught fire (probably from the exhaust), no way I could have stopped that one.
On the other hand, the fuel tank is at the back, so as long as the fire seemed localised at the front of the car I wasn't too worried of an explosion. But as I said the whole thing was completely pointless - if you see a burning car just stay away and call someone who actually know what they are doing i.e. the firemen.