12:30 I'll be short tonight as i drove 220 miles and i'm kinda tired though i got something to say. I think i figured why i always get better mileage with fresh gas, no matter the station. They put in the gas some additive to increase octane number that is volatile and goes away in a couple of days.

But first let's take a look at your fuel tank. It is connected with a charcoal canister that catches the vapor and releases them in the intake.

The two major addition to the intake manifold of modern engines, besides injectors, are PCV and EGR systems. I was intrigued a long time with those until i figure what they do.

PCV relieves pressure build in the engine by exhaust escaping the rings of the pistons and recirculates them in the intake, instead of releasing that exhaust in the air and polluting, and EGR that also recirculates a small amount of this time exhaust exhaust back into the intake, with the purpose of slowing down the burning, with an effect similar to using higher octane fuel.

While PCV works with the vacuum of the intake, increasing return at higher vacuum, EGR is computer controlled. I believe PCV complements the EGR since some of the blow by is exhaust. So here we look at the concept of reducing pinging while increasing timing with the help of exhaust used for decades.

Raw exhaust (before the catalytic converter) returned by EGR contains mainly carbon dioxide and the inert nitrogen that passes unchanged through the combustion chamber.

I did few google searches to make sure. First, if CO2 can be used to improve octane number in a fuel and the answer was no. However, indirectly google said that CO2 can be disolved in gasoline and we know that CO2 from EGR slows down burning.

I think you know by now where i'm getting at. Theoretically you can dissolve CO2 in gasoline and that would slow burning, with the effect similar with using a higher octane gasoline, however, CO2 being volatile it can escape the tank through the evap system in a couple of days in a way similar to soda going stale.

I think the underground tanks in gas station are sealed, otherwise we will fill a smell. More than that, modern pumps have a return circuit for vapors displaced from tank. No i don't believe gas station owners know about it, if it's happening, it's happening at the point where they add the additives and even those gusy might not know what's in those pressurized bottles.

With today's knock sensors and stuff, you can use a variety of fuel grades because the system will adapt, however, you will getter poorer mpg with lower octane gas if only because the timing needs to be lowered to avoid pinging which lowers efficiency thus needing more fuel for the same distance and money.

But we have to somehow explain the phenom on of gasoline going "stale".

Anybody would try to take a sample in lab for analysis would seal that bottle and the gasoline would not go stale.

Yes everybody can easily verify this theory without any lab. Find a window with three days of constant weather including the wind, rain, etc.. Go to a gas station, fill with fresh gas and drive 50 miles at night somewhere where there's no traffic. Do not modify tire pressure. Do the same thing two days later at the same hour (in a word, in identical conditions) with the gas left in the tank.

But first you have to identify, using the manual, the MPG indicator on your dashboard.

If so, i can see here the shadow of a huge scam but i really don't believe they're doing it for money, as for religion reasons.

As i tried to explain many times, there are at least two sects, one Christian (Dominicans which are most influential in the Catholic Church) and possibly Zen Buddhism interested in either rushing in the apocalypse for the purpose of rushing Christ back on Earth or heating the planet as in Buddha's Sermon of the Seven Suns thus bringing Nirvana (extinguishment) for all to end all sufferance and death-rebirths cycles.

1:00 AM Yes i had to fill at the station on the hill in Warm Springs and for some reason i fail to understand, Super gasoline was almost 2 dollars over Regular (got a picture to prove it, tomorrow) so i filled with Regular. This way the instant mileage for the trip was 45, with Tualatin being some 1300 ft below the starting point, and with fresh Plus the way the car is setup right now, with new injection coils, would have probably been 48, beating some hybrids (on freeways where battery doesn't matter).