This is definitely Ron Wolfe's "The One-Shoe Blues" (1985). It can be read in its original context online courtesy of the Internet Archive.
He looked toward Lyn again. She was driving like before, tapping out
the rhythm of the "One-Shoe Blues" on the car top.
At the same time, Charlie couldn't help noticing, she had both hands
on the wheel.
He fingered the door latch.
"Suppose," she said, "suppose... there is no monster, Charlie. But
suppose there is a... very different kind of life, from a different
kind of place. Lost here, through no fault of its own. And it can
change shapes, like on 'Star Trek.' Suppose... it could not make you
understand how it does that, except to that it breathes in the
feelings all around it."
It's not the protagonist that gets eaten, but another hitchhiker after the protagonist's escape.
He turned just in time to catch a glimpse of the candy apple Corvette.
There were bits of glitter in the paint finish. The girl driving it
wasn't wearing any top at all that Charlie could see, and her hair was
done up in a blond swirly-cue like Dolly Parton.
The car sped past him, and was almost out of sight when Charlie saw
the driver toss out something small and brown.
Before long, he found the other shoe.