First, you should probably watch the video itself, because it’s absolutely bonkers for a number of reasons, not the least of which is the odd calmness of the Kiwis watching it happen.
If you’re impatient, the part where the bus actually starts up and drives on its own happens at about 3:25 as you can see and hear the bus attempting to start, and then actually getting rolling along there, where it crosses the street, hops the curb, and sets some trees aflame by the tennis courts that are on that side of the road. This actually worked out well for the RV’s owner, as it got the vehicle away from his house, even if it did end up setting even more stuff on fire. So, why did this RV decide to become a very short-lived Level 5 automated vehicle with FSD (Flaming Self Driving) for the last few seconds of its life? Even though the video description reads …nothing about this is really a mystery, and, in fact the clues to what is going on are mentioned right in that description. Specifically, when they talk about the lights turning on. We also get audio clues in the video from the horn blasting a final mournful wail, and the sound the engine makes as its being cranked over. Tellingly, all of these events that happened as the bus burned – lights flashing on, horn sounding, and the engine cranking – are electrical. What’s going on here is that as the bus is burning, plastic and rubber insulation from the electrical wiring is being melted away. The 12V battery in this RV is very likely mounted pretty low in the body of the RV, and the fire is raging primarily in the upper section. That means it’s likely the battery is still relatively intact and providing voltage while everything is on fire. What appears to be happening is that wires to various electrical systems, like the lights, is having insulation melted off, which will allow bare, conductive wire to make contact with other insulation-deprived wires that are hot, electrically and literally, carrying 12V from the battery. When these touch, it’s like closing a switch, so the headlights can blink on as their uninsulated wires contact 12V lines, same for the horn, which honks when its bare wires contact 12V wires, and finally, the starter motor can crank the engine when its thick, heavy gauge 12V line direct to the battery loses its insulation and makes contact with some other bit of wire or metal that closes the circuit to the starter motor. This being New Zealand, it’s very likely this RV has a manual transmission. And, it’s likely it’s parked while left in first gear, and the parking brake does not seem to be on or particularly effective. So, when that starter motor’s circuit is closed, the starter is turning the engine, attempting to start it, and the RV is in gear, so that turning engine is spinning first gear which is turning the driveshaft and the wheels and the result is the burning RV ends up driving itself. You can hear the telltale sound of an engine attempting to start while being cranked by the starter motor, and it continues until (and a bit after) the RV hits the trees on the other side of the road. The engine is too damaged to actually start, but the starter motor is strong enough to keep spinning it and moving the whole burning mess. I’ve heard about this happening before with other burning cars, and while it’s always weird, it’s not a mystery, and it’s not a ghost. I don’t know for certain that this is the explanation for what happened, but I’m pretty damn confident, based on everything you can see here. It’s always kind of fascinating and shocking when this happens, because if a huge van on fire makes you uneasy, a huge van on fire driving mindlessly with no control is far, far worse.
