What is your method in calculating MPG?

[acranox]

I always write down the odometer reading on the receipt when I get gas. And I always fill up until the pump shuts off.
I put the info into a spreadsheet and keep track of all the stats.

 

[olympic]

As above, miles driven/fuel volume pumped. Total everything up after 4-5 tanks of fuel and any variation in pump meter accuracy and how full you get the tank will be insignificant.

A couple of my vehichles have an "average fuel economy" computer and I have found them to be quite accurate. You can reset it and get the average MPG over a single trip or let it run all year and get a true picture of fuel economy over varied driving conditions.

 

[TooManyWheels]

I only calculate economy for highway driving, as I believe my driving within a large city has way too much variability to support a meaningful test.

For the highway, I only take seriously the data from the run I make repeatedly. I fill up at the same stations just off the highway on each end, letting the pump shut itself off. I also note how much load I am carrying in the vehicle, and whether I ran the A/C. I disregard any trips where I have to do any idling due to accidents, road construction, etc.

 

[XS650]

quote:

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Originally posted by olympic:


A couple of my vehichles have an "average fuel economy" computer and I have found them to be quite accurate. You can reset it and get the average MPG over a single trip ....

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Same here. My driving is varied enough that the mileage on any one tank doesn't mean much.

I use the computer on highway trips to get my highway mileage which doesn't vary as much. That way I don't have to fill at the end of each trip or segment of a trip to see what happened.

When I have checked the computer against carefully filled fillups, the computer has been real close to the pump/odometer calculated values. My gut feel is that the computer is as accurate as the roughly .25 gallon variation in fillups based on different pumps and tank filler's patience.

 

[Steel Blue Wind Rider]

Yes, I do the same, by keeping records in MS Excel, I know which gas gives me the best MPG. I have records from day 1, usually average by month. I separate highway trips to get a more accurate account, but to be honest, most of my miles are mixed highway & city, which reveals true day to day MPG and costs to operate.

 

[eljefino]

Here's a DUH idea for Exxonmobil: When someone uses speedpass have them enter the last 3 digits from their regular odometer. Repeat at the next fueling and the pump will automatically compute your MPG. I'm sure their credit card has an online feature; they could merge databases and you could access with your browser. Upon initial registration you give them your full mileage; it then assumes you rolled another thousand if the new 3-digits is lower than the last. (assume noone goes more than 1000 miles per tank.)

This would be a great loyalty thing; people would pay extra for mobil/exxon fuel in a strange town so they don't screw up their database. And they could steer you towards their credit card for maximum benefit.

 

[Patman]

I simply switch to the MPG display on my dashboard.

I found it to be very accurate, so I don't even bother figuring it out manually anymore (which is probably less accurate, especially if the gas pumps stop at a different time)

 

[tweeker43]

i use a little application on my palm (pilot) that takes date, gas station, miles, and gas. then, after every oil change i enter the information into a spreadsheet on my desktop. i normally keep about one or two prior oil change intervals on my palm.

there's not much as anal retentive as poking data into a palm pilot as your tank fills up.

except maybe squirting in a dose of fuel power, using a screwdriver to hold the little metal flap back.

mmmmmmmmmmmmmm, dorky.

 

[Jackpot01]

All I do is fill it up, reset the trip meter, when the light comes on...fill up the tank, divide the miles on the trip meter by gallons I put in. I have a spreadsheet I made to track mine. Its ashame that I cant get over 30mpg average in my Focus

Eric

 

[tenorGJ]

I'd like to sample a few posters' methods of calculating MPG. I've been dividing the gallons of fuel capacity by the miles driven--a spotty way to do it, at best. I imagine an average would be better. How do you calcualte?

 

[Quick_lude]

fill up the tank completely. Reset trip odometer to zero. Drive. At the next fuel stop, once again fill up the tank completely. Divide the miles on the trip odometer by the amount of gallons needed to bring the fuel tank to full. Voila, works everytime unless something prevents you from filling up full.

 

[T-Keith]

Quick_lude has it. Remember there are slight differences in pumps and stations so more then one tank may be needed to get an accurate reading.

-T