When the bad guys set off an explosive charge to blow out the front tire on the Chevrolet Col. Austin and his friend are driving, the closeup of the tire blowing is that of of a bright red Volvo, a completely unrelated car. Check the hubcap difference--note the "V" logo.
The sedan Col. Austin and his friend are issued is a shiny new red Chevrolet. Near the end, the Col. turned the car over on a henchman. In the closeups, the paint is dull, scuffed and the bodywork dented. Not the same car at all.
Steve and Fred are driving in a red Chevrolet Impala/Caprice with a red interior, but the shots of the dashboard, when Fred floors the accelerator and the speedometer increases, appear to be from a Chrysler-manufactured car (note the design of the gearshift indicator and steering wheel) with a black interior.