Back around 1968-73, I lived in Somerville MA. And we had a LOT of car fires..
At the time, our city was one of the most densely populated cites in the USA.
80% of the cars that burned up, were very large gas-hogs..
I did see a pickup burn on Rt-3.. As I came up from behind him, he had pulled over with some smoke from under the front end. As I went by, he was running away from the pickup, the fire was starting to blaze.. Within a matter of seconds, I was about 1/3 of a mile ahead of him, I saw the flames shooting up in a wide column of fire, about 80 to 100 feet tall.. It was amazing, the pickup was totally engulfed in a ball of fire.. It must have been down to the bones within minutes..