This should apply to pretty much any mod or game, I imagine. In response to Andrew, here's how you can find precise fuel usage. Go into motec and load up your lap data from your test laps. Now, in the drop-down in the top left (Starts at "Samples") select "Engine". In that section, the second tab reads "2. Fuel". Click on that tab.

There's a whole bunch of useless stuff there, but what I did (if it wasn't there by default) is right-clicked on that page of charts and selected Properties. This lets you configure the set of graphs shown on that tab. Click "Add Group" which ought to be "Group 7" in the list. Now click "Add Channel" and in the list of channels, select "Fuel Level". Mine is measured in litres (l), but maybe your region will make it gallons or something. Click OK there and then OK in the properties window. Now, for a given lap you will see the fuel load that started at the left and on the right the fuel load at the end of the lap. Also, you can scroll down with your mouse wheel in that display to change the level of zoom. So if you scroll all the way out, you will be viewing the entire stint and can see how much you used over the stint.

This does require doing a quick calculation of start to finish fuel load. I am not sure how to make Motec calculate this for you (if possible) but it would be nice to have it show the result on the top right of the line graph or something. Maybe Steve could point that out if it is possible?

Justin and Fellow motec users Create a Worksheet that is a channel report. Then add Fuel Level to it, then one of the check boxes is Value Change, click it. Then motec will give you how much fuel was used on each lap.

Thanks for your reply Justin.
What you've explained is as far as I've gotten myself.
Surely there is a "math channel" (no idea what that is, but it sure sounds like it might be useful :p) that will allow you to calculate fuel use over a lap. I know that you can use math channels to calculate things such as total steering angle per lap.

EDIT: looks like Michael has tackled the issue himself. Thanks Michael!

Thanks Michael! Such a simple thing once you know how to do it. Like programming software or brain surgery!

I looked at using a Math to do fuel calculations, but the crucial data that isn't available is the lap number...it's just not available in MoTeC...in fact MoTeC itself creates it on the fly, but for some reason isn't sharing it to the Maths. So, for fuel determination I just divide the fuel change by the number of laps. But, after taking great pains to do fuel calculations before each race I've come to the realization that rFactor does an excellent job of estimating fuel...if it says you will do 10 laps than that's how many laps you can go when you leave the pits...including your out/in laps. There's some small variations depending on how much boost you use or wing settings, but not enough to worry about...you will quickly learn how many clicks to go before or after the lap estimate hits your desired lap number for the way you like to setup your car and drive...then just use that process at each track.

True Steve, but I've also come to find that Rfactor can give you a couple laps too much fuel (even when my fuel calculations have 10% extra fuel for spins) depending on the kind of car you drive.

Just my experience. Better to drive on less fuel if you can.

Now GTR2 on the other hand..... not so good with fuel in my experience.

Yeah GTR2 works well with some tracks and not so good with others...and seems to vary much greater when you change driving style or setup. It saves a lot of time to keep a spreadsheet (excel or whatever) to keep the fudge factor available...it's fairly easy to see how much fuel was used in x number of laps and divide it to see what fuel is used per lap then multiply that by the number of laps you want to run, but when you have 20 easy things to do then eliminating one of them makes life so much better.

Rfactor does a good job of calculating the fuel ? apparently you've never tried the F1 1979 mod LOL.

What I do is try to set 3-4 consistent laps and then calculate the fuel pr lap using Motec. Doing it on just 1 lap is a bit risky.

I think the default rFactor mods tend to be ok when it comes to the mileage. But nearly every other mod I've used has required me to do a decent length run and divide the total amount of fuel used by the number of laps (inc in/out)

Doing only 3/4 laps and then calculating has ocassionaly given me weird results.

what i tend to do in rfactor is run the plugin, do around 5/6 laps. then load motec up and work out how much i've used on each lap. This then gives a pretty good average of what i'll be using each lap and so far it's worked. I always add a few litres though just incase i have a few offs :)