1k / instant better mpg

[sde]

i've had the lgt 2 weeks and haven't seen it get better than 18mpg, .. today i hit 1000 miles and within 30 miles, my mpg jumped to 26. coincidence?

[GBY]

I think the gas formula changes in CA around this time of the year. I know I've been getting around 2 mpg better mileage recently.

[sde]

hmmmm .. if the type of gas has to do with it, then i filled up at cheveron right before i got those results. i usually don't use cheveron since there aren't any right around me. maybe i will experiment with different brands / mpg now.

[GBY]

I mean the actual gasoline formula, I think they oxygenate the gas during the summer here in CA to help reduce the nasty effect on air quality that exhaust gases have.... It's my understanding that this kills your mileage. Dave.

[Xenonk]

It also depends on which gas station you get your gas as some companies have all these additives that claim to make your car run cleaner and such. I run Sunoco gas and Sunoco affiliated companies.. they are the only company I know that sells 100 octane gas from a public pump.. (depending on locations). [url]http://www.racegas.com/[/url] check for your local Sunoco Gas station for some GT 100 oct. fuel ;) [url]http://www.racegas.com/gt100locals/default.asp[/url] [url]http://www.racegas.com/distributormap/default.asp[/url] Keefe

[SBT]

Gumby, Believe CA requires oxygenated fuel during the winter, ostensibly to help engines run leaner and thereby produce less carbon monoxide in areas that are prone to CO pollution, e.g., SoCal. Colder weather, coupled with atmospheric inversions, tend to make CO pollution worse. Chevron has a faq sheet on this at: [url="http://www.chevron.com/prodserv/fuels/gas_qanda/oxygen.shtml"]http://www.chevron.com/prodserv/fuels/gas_qanda/oxygen.shtml[/url]. SBT

[SBT]

[quote name='Xenonk']It also depends on which gas station you get your gas as some companies have all these additives that claim to make your car run cleaner and such. I run Sunoco gas and Sunoco affiliated companies.. they are the only company I know that sells 100 octane gas from a public pump.. (depending on locations). Keefe[/QUOTE] Keefe, Do you run race gas all of the time or only when you're actually competing? If alternating, how long does it take your ECU to dial-in the 100 proof or do you do an ECU reset each time you migrate to the higher octane? How does your car run on the otherworldly starch... otherworldly because we only get the 91-92 juice in San Diego county. Have to run all the way up to OC or LA to get the race gas unless there's a new vendor in town that I'm not aware of. SBT

[Xenonk]

I run a mix of 93 octane and 100 octane at the track IF needed.. it's for safety reasons to prevent detonation. On a stock car, it's not going to do anything. In fact, it might not even burn it all efficiently.. it's when you decide to get engine management for higher boost, more fuel, and more timing, then you can run higher octane for anti-knocking reasons (or prevent your plugs and valves and heads from being all screwed up). On my WRX, I ran the car very close to 90% injector duty cycle and that's already a bad thing.. the car would knock a little bit if I didnt run a mix of 100 octane in the tank. I would mix the 93 and 100 to make 97 octane (3 gallons of 93 octane and 10 to 11 gallons of 100 octane does it.. do a search on google about fuel mixture octane charts online). So in the future when I am on the track in the summer on a hot day running with my engine management, (I am aiming for about 250 to 270 whp when all said and done), I will run 100 octane for the track. Keefe

[GBY]

[quote name='Subietonic']Gumby, Believe CA requires oxygenated fuel during the winter, ostensibly to help engines run leaner and thereby produce less carbon monoxide in areas that are prone to CO pollution, e.g., SoCal. Colder weather, coupled with atmospheric inversions, tend to make CO pollution worse. Chevron has a faq sheet on this at: [url="http://www.chevron.com/prodserv/fuels/gas_qanda/oxygen.shtml"]http://www.chevron.com/prodserv/fuels/gas_qanda/oxygen.shtml[/url]. SBT[/QUOTE] Thanks for setting me straight Subietonic, I had that the wrong way around. Going back to the original post, I've also been getting better gas mileage recently and have no idea why.

[nov26_2]

I have about 1200 miles and am averaging around 17-18 miles per gallon in mixed driving. I have been using 93 octane the last two tanks and 91 before that. You're saying it will take the ECU some time to figure out how to burn more effieciently? Does the ECU reset after it notices an octane change? I think I am too used to cars that don't think much--99 Honda Accord- I think I could run it on corn oil and still get better MPG. Any help to improve the mpg is greatly appreciated

[fbi012]

lol. [quote name='nov26_2']I think I could run it on corn oil and still get better MPG. Any help to improve the mpg is greatly appreciated[/QUOTE] me too I have bad mpg, any wayto improve it? could it be some part that has to be replaced? shall I note to my dealer the low mpg?

[Boostjunkie]

Winter gas in CA will always yield WORSE mileage, so if you getting better mileage, it isn't the gas. Oxygenated gas contains less energy, so you have to burn more to get the same amount of work out of it. Most cars experience a drop in mileage of about 2-5% when you compare unoxygenated gas to oxygenated.

[SBT]

This has been mentioned before that the Subarus do better if you roll gently into the throttle rather WOT and I know that my mileage suckett when I get my throttle on. Best mileage for me happens when I exercise restraint on the gas pedal, time my traffic lights and engine brake (without adding throttle) where I can to keep RPMs up so that I don't have to start off from idle or near idle. SBT

[Mr. CentralOhioSubarus]

Winter driving nearly always will get you worse MPG. The air is cooler and more 02 dense. This creates more horsepower, but also robs from your MPG. [quote name='Boostjunkie']Winter gas in CA will always yield WORSE mileage, so if you getting better mileage, it isn't the gas. Oxygenated gas contains less energy, so you have to burn more to get the same amount of work out of it. Most cars experience a drop in mileage of about 2-5% when you compare unoxygenated gas to oxygenated.[/QUOTE]

[SubieGTWagon]

[quote name='Subietonic']This has been mentioned before that the Subarus do better if you roll gently into the throttle rather WOT and I know that my mileage suckett when I get my throttle on. Best mileage for me happens when I exercise restraint on the gas pedal, time my traffic lights and engine brake (without adding throttle) where I can to keep RPMs up so that I don't have to start off from idle or near idle. SBT[/QUOTE] I got 18 MPG when my GT (manual) was new - now at 6k miles with a combination of keeping my foot out of it and smooth driving techniques I average 22 to 23 in mostly city driving. Set your trip computer to the real time gas mileage readout and see how much your driving style impacts your gas milage - it's interesting. The GT is all about driving technique if you want to get good gas mileage.

[SBT]

[quote name='Mr. CentralOhioSubarus']Winter driving nearly always will get you worse MPG. The air is cooler and more 02 dense. This creates more horsepower, but also robs from your MPG.[/QUOTE] All else being equal (same gas, properly tuned, same driving technique) there's something to be said about power robbing coldness, but once the engine and drivetrain is up to operating temperature, IME colder, denser air contributes to "better" gas mileage, to a point. Once it drops solidly into the freezing zone and stays there (< 32 F), I typically get less MPG. Can't tell you why this is, but I see it happen once the outdoor temp gauge settles into the sub-freezing area. Of course keeping the car in a heated garage, tends to mitigate some of this but I still see the drop in MPG if the temps stay sub-32F. SBT

[05USdmGTgUy]

[quote name='sde']i've had the lgt 2 weeks and haven't seen it get better than 18mpg, .. today i hit 1000 miles and within 30 miles, my mpg jumped to 26. coincidence?[/QUOTE] I think that the issue here is that when you filled up the tank you probably reset the trip odometer which in turn reset's your avg. mpg guage!!!! Just a guess. :) MIke....

[Bob N]

I hit 1,000 over the weekend and looking at the readout, I was around 24.5 to 25.5 before 1000 and now I'm at 22.5 to 23.7. I think part of my problem is I have a tendency to "get on it" once in a while. I really don't think that 1,000 miles and better gas mileage go hand in hand. I would think it would be gradual (due to break-in) not sudden.

[flat4fantasy]

FWIW to the So Cal'ers, The 76 station at the end of the 110 N fwy in Pasadena, Arroyo Seco Blvd? and damn, dunno the cross st. But wherever the freeway ends...that station has sold 100 octane for YEARS. It's a huge temptation to fill up and haul ass down the 110; god I love that freeway's twisities! Dave

[axis008]

[quote name='flat4fantasy']FWIW to the So Cal'ers, The 76 station at the end of the 110 N fwy in Pasadena, Arroyo Seco Blvd? and damn, dunno the cross st. But wherever the freeway ends...that station has sold 100 octane for YEARS. It's a huge temptation to fill up and haul ass down the 110; god I love that freeway's twisities! Dave[/QUOTE]Is that 100 octane leaded or unleaded?

[Boostjunkie]

The 100 octane sold at Unocal 76 is unleaded. Regarding mileage, I have yet to crack 20 mpg for a whole tank. This is mostly due to the bulk of my driving being short trips around town and when I do get on the freeway the temptation to boost it up is just too great to resist!