First up are SSPs, a car that worked because it had one big wheel that you made go fast, and lots of little weels to run on. You make the big wheel go by putting a tabbed strip into a slot. You then pulled fast, the tabs on the strip grabbing onto the gears around the wheel. You then made your cars go, usually across the driveway and out into the street. Look at the video below to see how it's done. Naturally, the commercial makers made sure that the cars flew along much faster than the toys actually operated at. To be honest, I don't remember which cars we had or our friends had. What I do remember is that we had the Demolition Derby version of the cars which popped off doors and hoods when they wrecked.
Don't let the bad fidelity of the YouTube recordings fool you: these commercials were VERY colorful and well filmed, and the car sets themselves were very colorful.
Of course, we as boys wanted them all but never got them all. NOBODY ever had the whole set of anything, no matter what the commercials told you to do.
And then we come to Evel Knievel. This was the second sort of toy that made cars go fast. Many varients of this type of toy were produced, including one that was just a wheel that you spun up and let go. However, the most noteworthy was Evel Knievel, THE stuntman of the 1970s, and pretty much the 1980s as well since there was nobody else like him. There was also a wheel form of this set, but searching for "wheel" and "toy' is pretty much a useless endeavor.
What led to the demise of these toys? Besides time and fashion, of course. My suspicion is that the late 70's led to an explosion of carpeting, which is nowhere near as good for racing as linoleum or bare wood. Or mabye I just grew up some and stopped noticing all the cool boy toys. I should look at a few period toy catalogs to get a better idea of when intertial racing toys fell out of favor.