I think that you are closer to the truth than you know. Something about this whole story is cockeyed and yours is the best angle so far, in as much as she was involved with these people and not on the fringes.
I figure she talked to much...
Burning is an excruciatingly painful way to die. This was a marker laid down as a warning to others. If they wanted her dead, they would have just shot her and been done with it. No, they wanted her to suffer. The gas in the mouth is that she "talked" to someone...
Yep. In fact, if I were to try to speculate a scenario, I’d say that “cleaning out the car” meant “delivering to someone.” That going to get gas was also a cover for asking Ali where/when to meet, possibly picking something up for him. That she met them where they were waiting, that she delivered but there was something wrong (they got ripped off, or they wanted something, or they were rivals, or they thought she was a narc, or she HAD turned narc, or someone she’d introduced them to turned out to be a narc... she realized her danger, tried to get away, they rear-ended her car and she put it in park and got out to... make a run for it? If her car was positioned such that she couldn’t drive away? They caught her, beat her, poured the gasoline on her and the car (covering something, no doubt. One of them must have been in her car at some point and this would be to eradicate those traces.)
Sounds very likely, especially the gas in the mouth/talking.
And the local po-po seem entirely uninterested.