The French Connection. While maybe not two cars chasing each other, a commandeered Le Mans chasing an elevated train made for some good action. Plus, the traffic situation was realistic. We all know what it's like to drive in bad city traffic, not to mention in the wrong lane under an elevated train platform. The realism of the situation made it all the more intense. I mean, how many of us actually have jumped cars over uneven streets like in some of these crazy car chase scenes? (OK, maybe once here or there)
Plus, the shooting scene at the end was a little more realistic than most modern day movies where guys endure the unreal and even dodge bullets. Here and exhausted Popeye Doyle (Gene Hackman) just shoots the bad guy in the back, right through the heart and it's all over.