What's the correct way to think of fuel-ups?

[peerenboom]

I've always wondered about the correct way to think of fuel-ups, and how I'm supposed to be entering data.

For the longest time, I did as the prompt told me - miles since last, gallons, price, etc. Entered in the data from one receipt of that most recent fill-up

But recently it was the "miles since" part that through me off - why would my miles, and calculation of mpg, be associated with the newest fill and not the gallons from the last fuel-up?

In other words & broad example:
- Fill-up #1 of 9 gallons.
- That 9 gallons takes me 210 miles.
- Fill-up #2.

So more recently, I've been keep the receipt for fill-up #1...until fill-up #2 where I can record the 210 miles that the 9 gallons got me (at whatever price and gallons).

Is that the correct way to think of it - 210 miles was achieved from the 9 gallons in fuel-up #1, and I'm always going to have one receipt waiting until the next fuel-up? Or the way I used to be doing it?

Thanks!

[Draigflag]

Yea I know what you mean, sometimes a tank of fuel will last me over a month, by that time, the price has changed a lot, but I still put the price I just paid as that's the fuel I just put in.

[trollbait]

How do you know the 9 gallons added for fill #1 was actually all used to move the car those 210 miles?

Using the price per gallon from fill #1 for the fill #2 gallons gives the price per mile for the tank just driven, but what about overall operating costs? How do you account for the cost of fill #1? For fill #2, the money just spent, is it treated as still in your bank account until fill #3?

Let's look at a gas station. Something happens in the market, and prices go up. The station already paid the old, lower price for the fuel in its tanks. It increases the prices despite that, because the pump price is set to what it will cost to replace the fuel in the tank.

The gas from fill #1 was used for fill #2, but you likely aren't going to pay the same price to replace it.