I dunno, you always hear people talking of crazy high gas mileage numbers here and there. On the VW forums, there are people talking about getting consistent 28mpg and even seeing 30mpg occasionally in R32s, but with mine - having the cruise set @ 65 and going from San Jose to SF the computer will never show more than say 22-23mpg and calculations usually back it up. I got it up to 24.5mpg going 70mph from LA to Phoenix.

With my WRX and Vishnu -0 I could never see more than 22 or so mpg when other people with more aggressive mods were claiming higher. Usually I try for mileage w/ the cruise control since I feel the car is better at controlling the throttle in a sane manner than I am.

I never got higher than 20-22 with my RS either.

 

i have 15.9 gallon tank. when the gas light comes on i hit aronud 230miles. so that gives me around 15 to 16 MPG. that is going 70mph on freeway. i went 60 before but still gets around the same mileage.

my 6mph is at 3k RPM and 80 is at 4k RPM.

 

Im still getting 13-16 mpg.....


Although I drive like an ape on crank.

 

omg, I don't think I could survive on 16 mpg...

 

Ok, I think this is all bull****.

What the **** does expanding gas have to do with better fuel..
Either way if your fuel expands it still fills up a fuel tank.. so what does the "expanding" fuel have to do with how your injectors spray it into your engine for combustion?

It cannot be any more than just a fuel mixture if there "truly" is better MPG.
Otherwise until someone provides a scientific response as to why expanding gas would provide better MPG its all idiots saying its true.. because they don't analyze anything.


And gas will fill up your tank the same in summer OR winter.. gas is temperature treated before it is distributed from the pump to your tank.. so it could be 100 degrees outside today, and 20 degrees outside the next day and either way it exits the pump the same temp. Otherwise you could say "at night I get better gas fill ups than during the day" because of temp change.. lol.

 

so our cars change the tune based on real time weather changes?...

lol

 

Winter fuel has more additives. An example is butanes. Which I'm currently off to go load 8 rail cars.

 

I've noticed an increase in MPG as well.

 

To cliff note the research I did on Teh Internets:

Gasoline is not pure... there's other stuff in it (I don't know why) and the different chemicals mixed in have different evaporation temps. In the winter, stuff with low evap is in there so that you can start a car that's been sitting outside in the freezing cold. These same chems in the summer are not good because they evap too easily, possibly resulting in "vapor lock" which causes "hard starting, a lean mixture, heavy hydrocarbon emissions and poor converter light-off."

The winter components, which make it easier to burn in the cold weather, reduce the effective fuel in the gas mix: "The oxygen-bearing compounds displace fuel components, so it takes more fuel to get the job done. Normal gasoline has a stoichiometric ratio of 14.7:1, reformulated winter fuel runs between 14.3 and 14.4:1" . This is why we get less mpg with the winter mix.

Nice article at:

http://zhome.com/ZCMnL/PICS/winterGas/winterGas.html

 

I am starting to get better MPG... but I thought it was due to the fact that I finally changed my oil...

 

I know the Costco gas in Livermore has a nice big sticker stating that the pump does not regulate volume based on fuel temperature. Obviously, everyone knows as anything heats up, it'll expand. Injectors also do not regulate volume based on a temperature, so however your gas is, your injectors will squirt the same amount of volume of gas either way. Obviously this is such a negligible amount, that driving habits would affect gas mileage more than this expansion size.

Amazingly, our cars can. The ECU has correction values that it can adjust to depending on what's going on in the cylinder. If the knock sensor picks up knocking, it can alter the fuel ratio to add more fuel, and maybe pull off some timing to fix that. If it's running fine, it may try to back off the air/fuel and try to run a bit leaner since you don't need the extra fuel. As an air charge gets warmer, the density of the air becomes less and doesn't require as much fuel.

While it can't "sense the temperature" it can adjust to conditions in the cylinder which are directly affected by the ambient temperature.

 

I forgot to mention that I mix 4-6 gallons of 100 race gas with 91. Maybe that plays into the 27.5 MPG.

 

How much do you pay for your 100 octane race gas?

 

Depends on location. 76 in San Jose on Almaden is like $6.03

Up in Redwood city on the 84, that 76 is like $5.89


I do it to run the 93 OCt cobb OTS map. There is a noticeable difference. Cost is about $10 more a tank to fill up with the blend.


The blend can make a stock STI run better.

 

i got 320 on a full tank last time. i just kept it under 3k and it really helps cause i drive close to 50 miles a day. but yeah i also noticed the difference!