I liked how the story was developing especially your description, in the next to last paragraph, of the heat was very good.

I have three suggestions regarding words and grammar.

his butterball face red dimpled cheeks >…face with red…

Veering off to the left, nearly clipping a young woman in a flashy maroon Corvette, her blonde hair and dark almond eyes glaring at her as if Margie were some creature that should be killed.

This needs to be separated. >Veering off to the left, she nearly clipped a young woman in a flashily maroon Corvette. Margie gave her the finger, as the woman glared at her.

The motor started to make this awful clunking sound as a thick> ..make an awful…

The ending is what ruined the story. It was out of the blue with no explanation of how it happened. Was it an hallucination from the heat? It’s just my wild guess.

I think it would be an easy fix and any explanation would help the reader understand the story.