I bought my car with full tank.. so when it runs almost completely out.. Lets say with 250 miles...What do I do to figure it out?

 

Make a note of how many miles are on the car at your next fill-up, then divide that number by how many gallons of gas you end up putting back in it to fill it up again. So if in your case, you had 250 miles on it and when you went to refuel, it took 11.2 gallons of gas.

250/11.2=22.3mpg

 

this is what i do lets say u wait till 1/4 tank left to fill up, since its 14.5 gallon tank, 3/4 of that is 10.875 then u see u drove 250 miles, divide 250 by 10.875 and u get 22.988 which is about 23 mpg

 

It's probably not best to do it that way, because when the gas gauge reads Reserve, it means you have two gallons left. It makes me wonder if when it says 1/4 tank, is it really a quarter of 14.5, or of 12.5. I'm not sure, so I go by the fill up method.

 

or use the road trip thingy.

 

Don't they teach math in school anymore? I realize many people buying the car are relatively inexperienced drivers, but really, how simply is this? You take the miles you drove and divide it by the number of gallons you put in the car.

Even if you don't know this for some reason it's easily google-able.

 

it is self implied MPG....Miles per Gallon....miles divided gallons

how many miles did you travel divided by the amount of gallons in refueling.

 

As dgHotLava said Miles divided by Gallons. Reset the tripometer every time you refuel. Then divide the number of miles the tripometer read by the number of gallons you put into the tank. Voila. You have your MPG.

 

You can't geusstimate by 1/4 tanks and such because the gauge isn't an exact reading. reset your trip odo when you fill up and calculate on next fillup.

And don't top off...

 

The guage is far from linear!

Also, modern tanks are very difficult to fill to the exact level each time, due to long fillers and vent systems. The only way to get accurate readings is to record gas usage for several tanks of fuel.

I've never had a problem with topping off. OTOH, I don't top the tank off on a 100 degree day and then leave the car in the sun without driving it!

George <--who loves the 3 inch "straight into the tank" fillers on his VWs