Two favorites of mine:
Back in 79 or so, my Mom drove her 73 Dart into the parking lot of the local BurgerKing (hey, maybe this can transmogrify into an anti BK thread...). When she turned the key off, the car began to "diesel" as many carbureted cars of the day often did. Instead of knocking for a few seconds as it usually did, this time, huge orange flames began erupting from the grille and the seams around the hood. My poor Mom ran into the BK and asked if she could use their phone to call for help (before the whole 911 thing had become universal). The AH BK manager looked at her coldly and said, "lady, there's a pay phone right outside the front door. Having no coins with her, she pleaded again for help -- and got none. Bewildered, she walked out, hoping someone outside might lend her a dime for the call (yes, 1979 was a long time ago). And she watched the Dart burn. The idiot BK guy did nothing until the thick, black smoke started wafting into his restaurant, grossing out all of his eating (and ordering) customers. Car ended up a total loss.
Then there was my Dad's first Saab 99 (roughly the same time frame), and at the dawn of my knowing ANYTHING about cars. He and I had returned to his house, and were smelling gas. Stronger and stronger as we approached home. We opened the hood. With the engine running. And found a nice pin-hole leak in a pressurized fuel line, was delivering a nicely tight, squirt-gun stream of gasoline -- directly upon the hot exhaust manifold!!!!
I could see and smell the cloud/column of explosive gasoline vapor. My lucky day -- we got it turned off before the vapor found an ignition source. Car towed to dealer for (expensive) repair.
Engine fires are bad. Most people are totally ignorant about them. . .
