That’s pretty much what it takes once you have them.
What does kill bedbugs (though it takes repeated treatments) -
Diatomaceous earth (food grade) dispersed as a very fine aerosol;
Amorphous silica gel (CimeXa) also dispersed as an aerosol;
Sufficient dry heat to kill the eggs, nymphs and adults (high setting on clothes dryer for minimum of an hour);
Or for fast knock-down, spraying with organic pyrethrum spray, which paralyzes the crawling insects and has residual effects for up to a month.
Setting the car on fire is just an overly emotional response.