My favorite was a 1970 BOSS HOSS 302 chrome special you could only get by saving cereal box tops IIRC. I saved them up and sent them in.  It looked like - https://picclick.com/Vintage-1970-Hot-Wheels-Club-Redline-Chrome-Mustang-312220408079.html Later in life my girlfriend's son got them ... I had about 50 Hot wheels, a few of the rare models from that time. The double decker London bus. All long gone.