Originally Posted By: OneEyeJack
Gasoline should be getting better. Fuel systems on new cars are getting really complicated and smog control laws are getting tougher. Gasoline is going to have to step up, too.
It already has.
Allowable sulfur levels were cut from 1000 ppm per batch to 30 ppm average, 80 ppm max.
Benzene, which has high octane value, has been reduced.
Sulfur levels may be again cut to 10 ppm max.
Oxygenate was required, and later ethanol was made the only acceptable oxygenate here in the USA, although ethers are still allowed in Europe.
But the real issue with emissions from gasoline PC engines now has very little to do with this because the highest emissions from a gasoline PC occur in the first 10 minutes or so after a cold start, before the catalytic converter has the opportunity to warm up. Heavier hydrocarbons (which help give you mileage) in carbureted engines would lay down in the intake manifold and subsequently vaporize as the engine warmed up are now simply rammed through the system with fuel injectors.
We're slicing the skin of this onion very, very thinly these days.