I remember seeing "Sugarland Express" like AGES ago, and thinking it was pretty awesome. But then I saw it again, and it just didn't live up to my original impression of it. About all I can remember of it, off the top of my head, is that they got ahold of some old lady's '56 Roadmaster towards the beginning, and wrecked it. And I seem to recall a lot of the police car crash scenes just seemed forced and silly, more like a bad episode of "CHiPs", rather than "quality" entertainment of the time, such as "Smokey and the Bandit" or "Dirty Mary, Crazy Larry."
I think a better example of early Spielberg is 1971's "Duel", which is what really put him on the map. Although technically, it was an ABC Movie of the Week, and not a theatrical release. However, it proved popular enough that a few years later they shot some extra footage to pad the movie up to theatrical length, and put it in the theatres around 1974.
"Duel" is really just a simple, classic, "Man vs Beast" movie...even if the "Beast" is a 1955 Peterbilt 281. But it plays out pretty well, at a decent pace. And interestingly, the picture quality, i swear, almost seems like it could have been shot yesterday. It doesn't have that "70's look", for lack of a better word. Although I guess it's possible it was restored at some point.
It actually plays out like an extra-long Twilight Zone episode, although much of that might have to do with it being written by Richard Matheson. And the music was done by Billy Goldenberg or someone like that, who did a lot of early Columbo episodes. It has a sort of surreal sound to it, that seems one part "The Exorcist", one part "Psycho" and oddly, one part "Led Zeppelin."