I am surprised by two things - the number of other people who actually remember this film, and the number of people who remember it so fondly. As a matter of fact, my husband and I - who grew up on opposite sides of the country - both saw it when it came out in 1975, could never find anyone else besides each other (and our respective dates at the time) who saw it or even ever heard of it, and both remembered it somewhat fondly. I think because it never caught on and is therefore encased forever within the year of its release it serves as a reminder of our youth. Thus, if you are younger than about 50, I actually would not recommend this movie.
This movie truly has a great soundtrack and a great use of music in the action itself. For example "Locomotion" by Little Eva plays during a horrific slow-motion car accident scene. Someone else has already mentioned "Benny and the Jets". The other thing I notice about this film, separate from my own personal nostalgia, is that it takes chances that none of the homogenized formula-driven movie studios would ever take in today's film industry. It sets out to be a cross between "Billy Jack" and "American Graffiti", and hits the mark on some points (the visual feel of the film, the soundtrack), and misses the mark on others (little characterization or depth in plot). My six star rating is therefore somewhat misleading. If you were a teenager or in your early twenties in 1975, you'll probably see this film as eight stars for all the reasons I've given. If you are much younger or much older than that, you probably won't get it at all and for you it would be a four-star film. Thus, I split the difference at six stars.