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So, i stop pumping gas at the first click. and i try to go to the same gas station and the same pump every time to get accurate gas fill readings.

how important is this? sometimes it might just not be convenient or make me get gas 1 day early. it works out well because then i can get a consistent stopping point on the fills and a good tracking of the average gas prices.... but just wondering..

thanks,
Brandon

On modern cars, the FI gradually adjust to the exact mix of fuel they are putting out. By going to the same station everytime, your MPG will thus be slightly higher than if you change stations every 2-3 tanks. Additionally, fill level and calculations will be more even.

Net benefit to using the same station is probably in the .25-.5MPG range for a Civic-type car.

Thanks! so it isn't a huge difference but not totally negligible. i just got hooked goign to a station on one side of interstate, can't get there when going west, so i have to fill early sometimes. i suppose i could always change stations and be off for a few weeks, but i have been going to this one for all tanks but 1 since early march.

Side note - you get hit by those storms tonight up north here?

*Crosses fingers*

No, I live by Woodfield (I-90 West of O'Hare). Nothing big tonight, lots of branches and trees down this weekend, though.

yea, it went north of us too (huntley) lots of cool lightning but it skirted us and we didn't even get any rain.

same thing about last weekend though... that was some crazy rain!

Switching stations can give inconsistent fills depending on the slope and other possible differences between pumps.

Put me in the other camp: It doesn't really matter IMHO. Most stations get their fuel from the same refineries, and the only differences are the goop they pour in once it's in the station's tanks. (Cleaners, etc.) Not a lot for the car to "learn". (Also, my cars are too old to do that.)

More consistent fills are better for figuring tank MPG. However, if you average over enough tanks the errors will average out. So your short-term results will be less accurate, but over the long term there's no difference.

So it can be a little better to fill at the same station, same pump, same click-off if you can. But it isn't a big deal, and often is not worth the inconvenience to me.

-soD

I agree with going to the same station or at least the same brand. Be careful though, I found this local station would take the leftovers from other brands and dump in their tank. So you have a mix of Hess, CITGO, EXXON etc in it's tank. True the cost per gallon's cheaper but the sparknock and lower mpg wound up costing me more per month.

Improved accuracy is good but it's not worth the trouble when you average more than 500mi/week. I use any available pump at several stations. That probably explains some of the peaks and valleys in my MPG graph.

I'm wondering if people look at you strange when there are several open pumps but you're sitting there waiting for that one special pump. I guess we get enough funny looks on the road; what's one more at the pumps.

-

hahah true that! i do almost 500 miles per week too, and sometimes it just isn't convenient. or the gas station is packed and i might just take the first available pump. i have now switched from one station to a more convenient shell station on my way to and from work. i'll see if the different gas company has any effect on my mileage.
Thanks guys,
Brandon

Well I top mine off to avoid that dilemma. Although it isn't necessarily legal. :rolleyes:

Hi All:

A first click even at the same station and same pump is no guarantee of the same fill. The next time you are at that same pump, feel the flow though the nozzle when one or two others at a different pump begin filling. There fill affects the pressure to yours and with reduced pressure, you will get more fuel at first click.

Top offs guarantee accuracy on each mpg calculation and keep yourself out of the station one out of ~ 5 visits. They do take longer to pump however.

Regarding fuel types, the difference are so slight there will be no adjustment by the ECU other than the Winter/Summer change over(s) and/or when you find a non-ethanol laced fuel vs. the crap most of us are stuck with.

Good Luck

Wayne

I prefer to look at this from the fuel provider aspect.... how many companies actually provide the fuel itself for your area? In my area, one company provides the fuel for all gas stations in a 200 mile radius, they just add their little additives as it is dropped into the ground. Also look at the pumps used for each station, are they all similar models? If so then they should all have the same or similar cut off points which is usually governed by the state and feds.

I can't see it mattering at all. If you're calculating every tank, maybe you're a little higher up the pipe this fill, compared to next, it will average out.

I was watching this debate from the N/A point of view: it's may be more accurate, but impossible to begin with. My last 10 fillups happened at 9 pumps, 8 towns/villages, 2 countries. I have many trips other than my daily commute. With this small tank I have I fill up whenever I'm not sure I can reach the next 'eligible' station and I fill close to the rim.
Anyway, most of Hungary gets gasoline from the same refinery at Százhalombatta. Additives can differ, though. At the Western side OMV stations may get it from Schwechat, Austria, but I'm not sure about the details.

I've given up on trying to pack the tank and having my gallons and distance vary each tank with guess work. Looking at the Mileage Log you can see how tank fills vary with just about every vehicle. Example, you can see where one vehicle got 80.5mpg on 17.95 gallons and the same vehicle got 62.1mpg on 16.18 gallons of gas. They both were filled by the same person using the same filling techniques but one tank was on straight gas and the other was filled with E10.

I concluded if I wanted to know how much my OEM MPG gauge was OFF and how to set my SGII correctly I had to gain control of the gallons I add at each fill. First, I had to establish how many gallons I could put in my tank after running out of gas. It turns out my very first tank I was able to stuff 15.405 gallons in at fill-up which was the most gas I've put in my tank. I then ran out of gas by accident and could only get 15.185 gallons in, but that pump was not on a slope like my first tank of 15.405 gallons added. I determined based on my mileage I had .8 gallons left in that tank after Zero Miles To Empty (0 MTE). This was .5 gallons less than my '05 FEH tank which is 1.3 gallons left at 0 MTE. This was the reason I ran out of gas because I thought both tanks would be the same size according to the specs. I then had to verify the .8 gallons by checking out the .8 gallons at 0 MTE by running the tank dry again. I confirmed the .8 gallons after 0 MTE the second time I ran the tank dry and packed the tank at fill-up on level ground at 15.195 gallons.

At this point I know the size of my tank but still need to find out how much the OEM MPG is OFF and need to adjust the SGII to match the gallons I add at each fill-up. This would allow me to know exactly how many MPG I'm getting though out my tank and adjust the SGII accordingly.

After trying many ways to adjust my SGII, I determined the only way was to burn to a known level of gas in the tank and just add an amount at fill-up I know the tank will always hold. I could make minor adjustments of a tenth of a gallon based on where I know the tank level is when I get to the pump to fill-up each time. If I put 13.5 - 13.6 gallons in at fill-up always, I have full control of my fill-up and know my MPG through out my tank. This way I would never have a high fill or low fill and adjust my SGII to a permanent setting with the gas I'm burning at each fill-up.

If you look at my Mileage Log http://www.cleanmpg.com/index.php?page=garage&displayunits=MPG%28US%29&viewcar=2612 since January '10, you can see the MPG graph is almost flat. I can now refine my hypermiling techniques according to weather conditions and tell what works and what doesn't through out my tanks. My SGII is set to the gas I'm really burning now and I know how many miles on my trip OD I should be at 3/4 of a tank, 1/2 tank and so on. The whole idea of improving MPG is to know where you are through out the tank and make improvements if you can. When you have no control of every fill-up, your in the dark as to making adjustments in your techniques in changes to vehicle and weather conditions.

GaryG

I keep a running total of miles and gallons pumped, and adjust my Scangauge to that. After a few years, it's pretty well guaranteed to be accurate. ;)