what is a clean gasoline?

Answer 1

When talking fossil fuels, cleaner generally means less sulphur.

But it could mean gasoline with alcohol in it, which produces a little cleaner exhaust.

Or it could mean gasoline with additives that help dissolve varnish and other deposits in your engine.

Without knowing the context in which it was said it could be one of those three answers or maybe something else. Those three are the most likely answers.

Answer 2

Helmut, your statment "Some of the unleaded gasolines have proved dirtier than the leaded gasoline they replaced." is very untrue!
The fact that leaded gas has LEAD, makes it dirtier!
The fact of the matter is that there is NO clean gas. The reason being is because of combustion. Any burning will cause polution.
So the obvious answer is that we NEED electric cars.
Hydrogen cars are a MYTH! the cheap one on the market today cost around $1million. And not to mention we have NO infrastructure inplace for Hydrogen cars, where you gonna fill up? But we do have the entire west half of the US filled with electrical lines!

Answer 3

There ain't no such animal. Even 85% ethanol blend cannot be considered clean because o the inherent inability of the internal combustion engine to achieve full combustion.

edit:
Some of the unleaded gasolines have proved dirtier than the leaded gasoline they replaced.