How low to run out my gas when testing mpg?

[Evil D]

How low is safe to go when running out a tank of gas to test your mpg? Should i fill a gas can and put it in the back just in case or...? I know some cars (especially 22 year old cars) it's not a good idea to run the gas tanks dry. What's the actual tank capacity?

[festiva351w]

why do u wanna run it out of gas to check mileage? i've never heard of such a thing, running it out is not a good idea, if theres any dirt or water in the tank it's more likely to get into ur lines and filter, if u run it dry

[TominMO]

why do u wanna run it out of gas to check mileage? i've never heard of such a thing, running it out is not a good idea, if theres any dirt or water in the tank it's more likely to get into ur lines and filter, if u run it dry

+1. Instead, be really careful to fill it completely when you fill it up the first time, drive it for about 8 gallons or so, then carefully fill it again.

[kartracer46]

+1. Instead, be really careful to fill it completely when you fill it up the first time, drive it for about 8 gallons or so, then carefully fill it again.

+2 I agree, I actually did that process 2 times just to make sure the gas was fresh and I got an accurate reading. 1st time I got 30mpg, and the second tank I got 35 mpg. I have a carby car and I drive spiritedly in the city traffic here in Norfolk, so you should do much better. I did actually have one tank full of 89 that I used on a trip "highway miles" that yielded 41 mpg. Not sure if it was the higher octane or the constant 70 mph speed that got it. Good Luck in your research. Try different driving styles and I am sure you will find the combination that yields the best economy.

[Zanzer]

You don't have to run it super-low. If you pay at the pump you can do what I do. When you fill up there's typically a fuel amount on the reciept so just make a note of the mileage on the receipt. Drive the car until the fuel gets as low as you want to run it without running out. Go fill up again, then make a note of the mileage on that receipt. Then just use the gallons used vs. miles driven from the 2 receipts to figure out your mileage. Using this method you can check it at whatever level you want.

[JPT]

You don't have to run it super-low. If you pay at the pump you can do what I do. When you fill up there's typically a fuel amount on the reciept so just make a note of the mileage on the receipt. Drive the car until the fuel gets as low as you want to run it without running out. Go fill up again, then make a note of the mileage on that receipt. Then just use the gallons used vs. miles driven from the 2 receipts to figure out your mileage. Using this method you can check it at whatever level you want.

That's what I do. The more gas you use, the more accurate your MPG calculations will be, but never run it empty.

[Team Lightning]

I've read that the fuel keeps the fuel pump cool which is the reason that running out of gas is a BAD idea. I've heard of poeple that had to replace the fuel pump after they ran out of gas. I would just run it low as stated above.

[batstiva]

I typically fill mine to just before gas starts running down the side of the car, and run mine down til about 1/4 tank. I don't compute my MPGs every time, but I pretty much always write down the mileage. Usually figure MPGs once a month, or so. Pretty much average between 43 and 45. Not bad for a carby, eh?

And +whatever number we are up to on not running it all the way out. Just asking for trouble, IMHO.

[Evil D]

Yeah i don't actually want to run it out...that's what i was asking. I was just thinking along the lines of filling up with X amount of gallons and driving that total number out and just multiplying the miles by the gallons to see what the mpg was. How else can you know if you've used 8 gallons completely or whatever?

[wybnrml]

I was just thinking along the lines of filling up with X amount of gallons and driving that total number out and just multiplying the miles by the gallons to see what the mpg was.

No multiplying. Just fill it up, write down the mileage on the odometer. Drive around until your at about 1/4 tank, fill it up again. Subtract the mileage you wrote down the first time to the mileage on your odometer now, divide that by how many gallons it took to fill up and that is your MPG.

[Evil D]

Geez why didn't i think of that...now i feel dumb lol.

[Zanzer]

LOL We didn't want to say anything...we were just hoping you caught these:

You don't have to run it super-low. If you pay at the pump you can do what I do. When you fill up there's typically a fuel amount on the reciept so just make a note of the mileage on the receipt. Drive the car until the fuel gets as low as you want to run it without running out. Go fill up again, then make a note of the mileage on that receipt. Then just use the gallons used vs. miles driven from the 2 receipts to figure out your mileage. Using this method you can check it at whatever level you want.

That's what I do. The more gas you use, the more accurate your MPG calculations will be, but never run it empty.

Just messing with ya man :mrgreen:

[Evil D]

See this is the result of someone who's been driving a Cherokee for 10 years that only gets 15mpg on a good day. You find that you don't WANT to gauge your mpg because it hurts too much. Now it's kind of fun but it's a whole new ballpark for me lol.

[Zanzer]

Hahaha...I feel your pain man! My 79 Bronco with the 429 got 7mpg. Checking the mileage was the LAST thing I wanted to do. Every time I passed a gas station it wanted to pull in and I was like "you just ate!!!"


The first week I drove my Festiva, I thought the fuel gauge was broken :toothy3:

[Evil D]

LOL i thought the same thing.

How many gallons does it hold anyways? I haven't ran it to E yet and had to fill it completely up yet. I put 7 gallons in it but it still had 1/4 tank left.