When Sam Tyler first finds himself in 1973, he tells the cop who confronts him about moving his car that the Chevelle isn't his. He was driving a Jeep. The cop is apparently confused and asks, 'You were driving a military vehicle?' Anyone in 1973 wouldn't have questioned a Jeep as a civilian vehicle. Jeeps were very commonplace in many models - Wagoneers, CJ-5's and J-10 pick-ups for instance.
Safety cables are clearly visible toward the end of this episode where Sam is seen contemplating suicide.