Anonymous wrote:

Anonymous wrote:

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

you filled up twice in one day?

yes. I filled it right before heading out on a drive that would be about 480 miles round trip (one day.) I can usually do the whole trip on about single tank of gas. So the first have of trip was when I noticed the guage going down super quickly, like I was at 3/4 of a tank after an hour which obviously wouldn't get me there and back on one tank. On my way home I refilled tank in another state and only used a quarter of the tank after 2 hours of driving. So I guess the guage could be off, but since it was the same day just different source of gas I assumed the fuel was related.

You can’t rely on the gas gauge to measure fuel economy. It will read differently depending on how level the ground is, whether you “overfill” or not, etc. some cars have computers that will tell you your mileage. Otherwise, it’s best to find a nice flat place to get gas, fill the tank as far as you possibly can, drive till used up, then refill the same way at the same place.

PP’s are correct that ethanol reduces mileage. 10% ethanol will damage many cars still on the road. The absolute insanity of burning food for motor fuel is a subject for another day.

Anonymous wrote:

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

you filled up twice in one day?

yes. I filled it right before heading out on a drive that would be about 480 miles round trip (one day.) I can usually do the whole trip on about single tank of gas. So the first have of trip was when I noticed the guage going down super quickly, like I was at 3/4 of a tank after an hour which obviously wouldn't get me there and back on one tank. On my way home I refilled tank in another state and only used a quarter of the tank after 2 hours of driving. So I guess the guage could be off, but since it was the same day just different source of gas I assumed the fuel was related.

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

you filled up twice in one day?

I had this happen but I was driving more than usual and it was also a sign that the car (my first car, bought used and driven forever) was in its way out. It started just eating through gas and the fix for it was more than the car was worth.

But OP's car is "newish"

Anonymous wrote:

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

you filled up twice in one day?

I had this happen but I was driving more than usual and it was also a sign that the car (my first car, bought used and driven forever) was in its way out. It started just eating through gas and the fix for it was more than the car was worth.

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

Your definition of "great" is not consistent with the meaning of the word. A car that gets 26MPG in the city in 2023 is not great.

Anonymous wrote:I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?

you filled up twice in one day?

The winter blends of gasoline tend to give lower mileage. Also, cold weather depresses economy.

https://www.energy.gov/energysaver/fuel-economy-cold-weather#:~:text=Cold%20weather%20and%20winter%20driving,to%204%2Dmile)%20trips.
Why Winter Fuel Economy is Lower

Probably not.

One of.the weird facts I remembered from Mythbusters is your mood can affect your fuel efficiency. Driving angry can reduce your fuel efficiency by as much as 15%, which is crazy.

What do you mean by fuel type? Octane? Shell vs chevron? Ethanol containing or ethanol free?

The only one that could make a big difference is ethanol. Ethanol provides less energy than gasoline, so if you used a blended fuel, that could translate into the neighborhood of 5% lower fuel efficiency. Octane could make a difference if you were in a car designed for a higher octane, but not as much as 5%. More like 1%. And I don’t know for sure, but I don’t think gas brands make much of a difference.

Maybe you used a fuel with 10% ethanol first and then ethanol free later.

I have a newish Subaru Forrester. I love the car and the gas mileage has been great. But just in the last week or two I noticed I seem to be going through gas much more quickly. today I filled it up at my usual place before going on a short road trip and within an hour or a quarter of the tank had already been used per the gas gauge. I assumed there was something wrong with my car, but when I filled up the tank later in the day at another gas station the great mpg I’m used to seemed to return. So my question is - can gas from one station to the next really differ that much? Would that be the reason for having both terrible mileage and great mileage in the same day?