Funny you should bring this movie up. Watched it last night while on the tread mill.
Brought back many great memories of Santa Rosa Ca. in the late 60'sl
Frates Rd. between Lakeville Hi-way and Adobe Rd. Is where the drag race scene was filmed, and seen from the airport near by. It was the film site ,but not the actual spot portrayed in the movie. It has a marked 1/4 mile that keeps getting moved due to the city limits being extended. The cruising scenes were filmed in Petaluma too. The power lines and sub station, along with the double oak trees on the west hillside, plus the eucalyptus trees to the south are still there.