I just put my first fill up into fuelly, and it's already giving me an mpg reading. How can it possibly have an mpg reading with only one entry? Maybe I'm just stupid and am not understanding something, but this seems to be wrong.

 

Congrats....
They are very smart....
Just drive and enjoy

 

It's all theoretical physics, algorithms and voodoo but what it boils down to is fuel flow thru a fuel flow sensor and another sensor that tells the genie how many times the drive shaft goes round and round.
BTW, more fuel flows thru the sensor at 60 MPH in 3rd gear than does in 6th gear.
But who really cares? gerry1253 has the right idea. Motor on, challenge the twisties and be sure to wave at your fellow MINI people.

 

Fuelly is a website, fuelly.com

 

So you're saying websites get MPG? What fuel, LP, diesel, JP5?

 

 

You enter miles traveled and gallons fuelled up and voila, MPG! I don't understand what you're confused about.

 

Did you tell Fuelly both the miles and the gallons? If so, the program can divide the miles by the gallons to get mpg. Of course you can also do so with a bit of arithmetic or a pocket calculator.

 

I'm not a fuelly user so I'm not sure what data they ask for, but I do know that on the app I use on my phone one of the settings is whether the fuel efficiency calculation is based on the previous fill-up record or the current fill-up record. Maybe fuelly is doing something similar.

 

Ok This much I understand. Yes I put in both miles and gallons, but here is what doesn't make sense. The first field in the form is "Miles since last fill up", then the next field is "Gallons", which I take to mean the number of gallons that I just put in my car. So in theory, for the site to be accurate, it should be doing this:

Miles since last fill up divided by # of gallons in LAST fill up = MPG

But since I don't have a previous fill up, yet still have been given and MPG rating, my assumption is that it is doing this:

Miles since last fill up divided by # of gallons in THIS fill up = MPG

If it is indeed doing that second calculation and not the first, then this is a completely useless calculation as the amount of miles I drove since my last fill up has absolutely no correlation to the # of gallons I just put in my tank in relationship to the mpg I got on my last tank.

 

Actually so long as you're consistant that exactly what you want. Resaon being, once you fill up that should show how many gallons you used during your last tank of travel. So what the app or website does is take your miles driven / total used amount of gas. You will not know how many gallons you actually used during the last tank until you fill the tank up.

Another example would be a partial fill up (which I never do). Just before you take off you fill your tank with ~11.5 gallons you drive a while but your on a stretch of highway that won't see a gas station for a long time so you decide to fill up. Now you won't know how many gallons you actually drove until you get to a gas station and fill the tank back up to full. Only then will you know how many gallons you used during that time. Then take the ~210 miles / ~7 gallons and you have ~30mpg. Thats why it takes the current fill because that the amount of fuel you used

 

That is exactly what I was missing! I knew I had to be missing something. As I suspected, it was my brain failing me, not the website, haha. Thanks Grizld700!

 

No Prob