What happened to gasoline in the mid 1970s?

Norbert Schmidt said
That is all very different than my understanding. Gasoline is fundamentally a bunch of hydrocarbons. An efficient, clean vehicle would ideally only emit CO2 and H2O, wouldn't it? Any molecules coming out the tailpipe with both H and C in them are hydrocarbons which should have been burned during combustion. If hydrocarbons are coming out of the tailpipe then some energy in the fuel was not extracted during combustion which is wasted power and pollution. Is that not correct?

Do you think new vehicles are zero hydrocarbon emissions? You're sadly mistaken if you do.

Obviously my point went right by you. It's my opinion that testing for hydrocarbons is the wrong way to go about it. Engines should be tested for efficiency. The more work they can do per gallon of gasoline. More efficiency means more work done per gallon of gasoline, ultimately burning less fuel in the long term = less pollution.