I've searched and searched and came across two numbers mainly; 15.5 and 15.8. It doesn't really matter one way or the other as the fuel mileage numbers only change by a handful of numbers (less than one gallon), but it's something nice to know I guess.

If I indeed have a 15.5 gallon tank, my MPG is 27.09. With a 15.8 it's 26.58. And technically it wasn't in need of a refuel at the time of doing so but it was close enough, so maybe 28-28.5MPG.

 

is this a question?

 

Yes. Do '98's have a 15.5 or 15.8 gallon tank?

 

'98 tank is 15.5 gallon.

 

thats way better than me im getting 21 on these same nc roads with expensive gas tax

 

It does not matter what size your tank is. If you start with a full tank and drive 240 miles then if it takes 12 gallons to fill it up again you are getting 20 mpg.

Todd

 

I calculate my gas mileage by going from F to E. Just not to the point where I run out.

 

This is the correct way to do it.

This is not the correct way.

Fill the tank until the pump shuts off. Then drive until the tank is down to 1/3 or 1/4 or 1/8 left on the gauge. Then refill the tank until the pump shuts off again. Divide the mileage driven during that period by the amount of gallons pumped at the final fill-up. This is your MPG, as explained above.

 

And how much gas would be left with only an 1/8th remaining? I'm positive I said I did just that. Again, I use the majority of my tank, then calculate my mileage, all without running out or drying the pump up.

And what if your first 320 miles were all highway (absolutely no playing around), while the last 120 were back road/city driving with a few WOT pulls? Wouldn't my numbers be considerably skewed after driving the first 50 miles before refueling?

 

For the purpose of calculating MPG, it doesn't matter. The only numbers that matter are the amount of miles driven since the last FULL fill-up, and the amount of gallons pumped into the tank at the very next FULL refueling.

You would actually have to run the tank dry in order to correctly divide the total miles driven by the total tank capacity. If any fuel is left in the tank, then this method isn't accurate.

Then the MPG figure in question would be a "mixed driving" figure. If you want true city MPG and true highway MPG, then you will have to drive the car in such respective ways exclusively during separate tanks of fuel.

 

I was just saying; don't tell me it's the wrong way to do it, then say the correct way is in essence the exact same thing I'm doing. By driving to halfway between a quarter and empty, I'm leaving roughly an 1/8th of gas left.

Then why are you saying the correct way is to drive down to 3/4, 1/2, or 1/4? Now it's just technicalities. Either way, I'm not running my tank dry when it may only boost my numbers by 1-3 MPG's. Fuel mileage should be calculated by how you drive regularly and since I don't regularly drive strictly highway or strictly city, I'm not calculating as such.

Therefor driving 50 miles won't accurately depict my fuel mileage. But thanks for the answer, and helping me all the other times you have. I truly appreciate it.

 

It doesn't matter if it's 1/4, 1/8, 1/16, 1/32 or 1/64 of a tank left. All that matters is how many miles you've driven (starting with a FULL tank) and how many gallons you add at the next fill-up of a FULL tank. I don't know how much more clear I can possibily make this.

Fuel tank size means absolutely nothing, doesn't help AT ALL for MPG calculations, and is meaningless for this purpose. That's just all there is too it. I can tell you the MPG of any car in the world with my only knowledge being the amount of miles driven since the last FULL fill-up, and the amount of gallons added at the very next FULL fill-up. Doesn't matter what the tank size is.



It won't boost your numbers at all. That's the whole point. It doesn't matter if you refill at 1/4, 1/8, 1/3, etc. Running it dry will not change the numbers at all, because total capacity has nothing to do with it, as explained above.

Still not sure where this 50 miles thing is coming from.

I've tried my best to help, and explain in-depth. You don't use tank capacity to calculate MPG, period. It doesn't matter how much gas is left in the tank. If you fill up the tank, then drive 200 miles, then fill it up again, and it takes 10 gallons, then you attained 20mpg. 200/10. It's really just that simple. Nowhere in that equation does total tank capacity matter. Not sure why this has become so difficult to explain.