Hey guysFirstly, I would like to sound out a word of thanks to everyone here who has been helping me with my issues on XML. I have successfully created a simple XML gauge which gives the following information:Total Fuel QuantityInst ConsumptionTime to Empty Distance to EmptyFrom the above information, I am interested to link it with the onboard GPS in FS2004. I am sure you realize that we can use the GPS within FS9 to plot routes. What I am interested to do is to feed these information from the GPS to my fuel computer where I will be able to simply display relevant information if the pilot has enough fuel to make it to its next waypoint and its final destination.

Unless you have complex performance tables available, any calculations you derive would be valid strictly for straight and level flight.

hmm, what if I assume it for straight and level flight then?

As I said, it's the best you can do without complex performance tables available.As for getting info from the GPS... the SDK holds all you need to know in that regard. A full list of available variables are listed.