Chapter Two: Vecna's Curse - S4-E2
Continuity mistake: When El advances on Angela and her friends at the skating rink and wallops Angela in the face with the skate, her aim is upwards at Angela's nose for the impact. When Angela's friends sit her up in the following shot, the upper bridge of her nose between her eyes is cracked and bleeding as she screams in agony.
Chapter Two: Vecna's Curse - S4-E2
Continuity mistake: After Mike kisses El on the forehead, Jonathan is in the back grabbing his glasses from his pocket. In one shot, he's grabbing them out, and then the next shot has them at waist-level.
Answer: They're both muscle cars, but that's about the extent of the similarities. But the 70's were filled with a lot of muscle cars, so some car models may look a bit like another's. Billy's car is a late 70's Chevy Camaro (probably a ‘79). Mad Max's car is a 1973 Ford Falcon XB GT. Incidentally, the Ford Falcon was produced by Ford Australia and wasn't an American car, or even sold in America (as in not sold at dealerships).
Bishop73
According to the experts its a Camaro '78 with added vented side fenders.