system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does wrong fuel in the car damage the engine?
gpt
The difference between gasoline types comes down to "octane", which is basically the resistance to exploding from heat and pressure. A high performance car will want to cram more fuel and air into a cylinder before the spark plug sets it off, and additives are required to raise the octane so it won't explode prematurely. If that happens then the engine can be trying to spin backwards against itself and can break.

To make an analogy imagine you are in a playground and pushing someone on a swing set. What you would normally do is wait until the person has swung all the way back and then push them harder as they swing back down and away from you. But imagine your timing is off and you try to push prematurely, as they are swinging towards you! That wouldn't work very well and the force of them crashing into you could be painful. You might even break your wrist or arm! In an engine this mistimed burning of fuel results in something called "knocking" due to the sound it makes, and it can similarly result in parts breaking or deforming.