My girlfriend drove down to New York and back and she says the trip down took a lot more gas than the trip coming back. She said that wind currents may have had something to do with it, but shse was wondering if gas from one company would burn at a different tate than gas from another.
The gas gauge is not a precise instrument. The only things it really is good at is full.
Any variation in rate of combustion due to differences in the gasoline itself is going to be completely hidden by other factors: traffic, incline (i.e. “down to New York” might imply that the trip there contains more downhill travel than the return leg), temperature, etc. It’s slightly more plausible if she filled up with a different grade of gas, since the ratio* between octane and heptane could in theory affect the rate of fuel consumption for a given engine.
- Okay, technically the octane rating isn’t the actual ratio between octane and heptane. A gasoline with an “octane rating” of 91 combusts like a mixture of 91% octane and 9% heptane, but need not actually be of that mixture.
Gas in some areas is mixed with ethanol, which is going to reduce your gas mileage. Other than that, gas is pretty much gas.
One thing I’ve noticed in the past few years is that gas seems to be a lot dirtier than it used to be. I’ve had several cases of clogged fuel filters in the past couple of years, where I never had any problems with fuel filters getting clogged up before then. A dirty fuel filter is going to make your gas mileage drop, and if it gets bad enough can make the car run very poorly.
Wind makes more of a difference in gas mileage than some people think. Changes in elevation make a big difference too. Your car will also get slightly better gas mileage if it is warmer outside.
Well, I get much better gas mileage (or at least I used to, last time I checked) on out-of-state (Nevada) gas than I do on California gas. When I say much better I don’t mean “hey, the gas gauge is moving slower”, I mean 50-70 more miles out of a full tank kind of much better. No idea why.
There are different blends of gas, most (if not all) blends have less energy then pure gas. Depending on where she got it she may have gotten a blended gas on one leg then straight gas on the other. Though it’s not suppose to matter much, my experience is that in certain cars it does, and unquestionable noticeable (again in certain cars).
Most likely she drove with her foot down on the way to NY, and with a light foot on the accelerator on the way back.
One factor that might possibly contribute to this is elevation: if the areas where you’re using that Nevada gas are higher, the air density tends to be lower which usually means better gas mileage.
Generality: Anywhere along the east coast you’ll find gas with 10% ethanol, which causes a significant reduction in mileage. The change where I live in SE VA/NE NC went into effect in early July, right around the time I was getting ready to move to NC and really racking up the miles between old place, new place, and work.
We went back to Indiana for Xmas, and I got much better mileage on gas from WV and KY (even in the mountains), over VA and IN gas. The ethanol blends were prominently posted in VA and IN.