When discussing fire risk, I remind people that ICE cars have "combustion" in the name for a reason - its propulsion literally comes from controlled explosions using flammable liquids.
If your gasoline is exploding in the cylinders instead of combusting, you should use higher octane or adjust your engine. When gasoline explodes in an internal combustion engine, it’s called “detonation” and if it persists, it can increase the number of parts in your car rather suddenly.
It always disappointed me that humans haven't really managed to make the rotating detonation engine work. Its theoretical efficiency and power density is really high.
Now I'm imagining something like a fidget spinner combined with a Nuclear Pulse Engine[1] and it's awesome because I'm imagining that it can provide both propulsion and rotation...but I bet we need some great advances in material science before anything like it could exist.
A Wankel was what I thought of first, since it's the closest we've come to a rotational explosion engine, but I'm a space nerd so the combination of rotation and propulsion could make for some interesting applications related to space travel.
Technically a deflagration is also an explosion, it's just subsonic, whereas detonation is supersonic. Plenty of explosives don't detonate: they're called "low explosives" and gunpowder is an example, as well as normal petrol-air mixtures.