Ask HN: Does anyone else notice that gas runs out faster than usual

Unless you find a fast station that sells ethanol free gasoline (and you'll know because it costs more), gasoline is cut with up to 10% ethanol. 1 gallon of ethanol is equivalent to 2/3 a gallon of good old gasoline. So to keep things simple, if you buy 10 gallons of gasoline @ 20 mpg is 200 miles. But 10 gallons of gasoline with 10% ethanol filler is really 9.6 gallons, that's only going to get you 193 miles. That's a 3.3% loss. Probably not enough to account for your "much less" observation.

Now is right about the time that refineries and gas stations switch from winter blend to summer blend, so maybe there's something to that.

Check tire pressure. I had a prius and milage would drop significantly (60 to 50) when the tires were low.

Of course tune up.

Have you changed gas stations / brands recently?

They’ve probably rolled out the E15 again:

https://carbuzz.com/feds-fight-gas-prices-easing-ethanol-res...

Do you always fill up at the same station or same brand? Maybe they are adulterating the fuel (higher ethanol content, etc.). You can get test kits for ethanol content. Maybe your vehicle needs a tune-up? They could also be fiddling with the dispensing measurement, saying that you put in 12 gallons, when it was really only 11. Harder to check than you might think, since some operators were adjusting things to come out correct at like 5 gallons, or whatever the local authority was using to audit things. Also, internal combustion vehicles get less efficient as they age/wear.

>I've noticed that I get much less gas than usual for the same number of bars.

I'm having a hard time parsing what this means.

>- gas smells less like gas

Is it possible for a person to smell the difference between octanes? The higher octane fuels have lower volatiles, so that might affect the smell.

Ethanol-doped gasoline (E0..E100%) has a lower BTU per gallon and a higher octane per gallon, assuming the same base fuel is used (e.g. 91 octane + E10 vs + E15). However, if manufacturers are cheapening the mix (e.g. 91 + E10 to 89 + E15) then they can hold the octane level steady while reducing your miles per gallon by about half the ethanol percentage (so, E15 is about 7.5% lower mpg vs. E0, or 2.5% lower mpg than E10).

You shouldn’t be noticing more than a 7.5% drop between E0 and E15 gas, which would be a pretty hard swing in gas composition. What % do your figures show?

I’ve been feeling this as well. I was wondering if something was wrong with my car. I used to refill once a month but I’m doing two refills a month.

Calculate volume and distance between the past twenty or fifty full tank fullups and then calculate distance ÷ volume for each of those pairs. If the number has dropped significantly, you’re getting fewer miles per gallon. If it’s dropped by a few percent starting five or ten days ago, it may be ethanol content (see E15 threads). If it’s dropped by more than ten percent, and has stayed there or worsened over multiple fillups, you may have a failing battery (which fucks up lots of car engine sensors) or a dirty/failing “MAF / AFR / front oxygen” sensor (which causes the car to mistakenly use too much gas). If you’re a thousand feet or more above sea level and your car has started taking longer to crank before starting at the same time, you may have a failing battery (see above) or a failing MAP sensor (which could cause the car to use too much fuel for your altitude).

Maybe your tires need air or your engine needs a tuneup or it's windier.

Or not.

Gasoline and diesel usually sell by volume, and if the temperature of the fuel is cold when you purchase it, you get more kilos per volume than you do when the dispensing tank is warmer.

There is quite a bit more expansion & contraction of hydrocarbons with temperature than many peoople expect.

gasflation