Any small heater is a fire hazard due to the upholstery of auto and other materials, reduced slightly if you have a wagon since the cargo area increases the distance the heat is from a flammable material.

Where and how to place the heater is very important. I've reduced the probability of a fire by attaching the heater via a clamping action to a metal pan which is screwed to some 2x4's to keep the pan off the upholstery. Extend the wood past the edges of the pan so no metal ever touches any upholstery. Add other wood blocks to level the pan.

Any combustion or catalytic heater is going to increase Carbon Monoxide plus add another fuel source for a fire once the fire gets going.

A small electric heater is probably your safest BUT, depending upon your distance from the house power source adds the feed cord as a possible ignition source due to internal heating of the feed cord. More length equals more heat in the cord and it goes up rapidly the longer the cord.

This fire is MORE LIKELY TO BE AT THE HOUSE SIDE depending upon where the power is obtained from and how the cord is run. If it comes from an inside socket, the probability of a fire increases substantially.

Reduce this by obtaning a 12 guage cord of sufficient length and have someone inside AND AWAKE while you have the heater plugged in. Up to 50 feet for 1000 watts. Over that distance or higher watts ( over 1000 NOT NEEDED), you may have to make a ten guage cord. I say make since at ten guage the power capacity goes up and the plug configuration changes as a protection. ONE cord only, NO plugs in the middle since they add resistance and cause higher internal heating. Again, the fire is more likely at the house side with any power cord.

Use a SECOND cord from another socket at least 20 feet away from the one feeding the heater for your work light. This minimizes but does not eliminate the probability the heater and light will be on the same circuit.

I would strongly suggest taking some time off to do this during the day or delay until your days off where you can work during the daylight hours with someone indoors to watch the power supply end. A working heater in your auto is not worth burning down your residence.

Duane