I think this movie would be considered underrated for everyone who was in college or university by the '80s.
I'm from 76 so was very happy while watching this movie. Despite the simple and predictable history, the movie goes very well without became boring one single moment.
Willen Dafoe, Judge Reinhold and all others in first line are perfect for their roles.
It is very nice the '80s atmosphere of the movie about everyday life issues of people growing ages of that time, in a film almost entirely shoot at outside locations.
If you know what to expect from a '84 road movie about rivals driving supercars around the city and racing on route 66, you must watch this one.
And if you really enjoyed this movie, I strongly suggest you must watch another one very alike: "Roadie" (1980), with Meat Loaf in main role (IMDB tt0081433).