Cars have (or had, I don't know if they're still included) an electric lighter that you pushed in to heat up. It was basically a little metal ring that got really hot. So I think it probably is the heat.
I remember my friend also had a plasma lighter, that unsurprisingly used plasma to light things. It made a really scary noise in the wind and hurt like a motherfucker to touch. We were 18 and dumb.
It's the heat and no, cars don't come with lighters anymore. The power sockets are still there but they even come with warning labels to not try use a lighter in them. No idea what happens if you try.
Nah, that was all you. Nobody said smoking was a good idea. Just that it's stupid to create a fire hazard to make a car 0.0001% more profitable. You barged in with a weird non sequitur. I was just pointing it out.