ORIGINAL: Tomn
It might also be possible that your design is inefficient - overweight designs suck up a lot more fuel than normal. If you click on your model in the management tab, what does it say about your engine?
ORIGINAL: ramnblam
Edit: What is the oil move cost for that model in the design section?
it uses 76,5 fuel per hex

umm what else do you wanna know?
engine designe is at 51... thats really low, isnt it?
it has a weight of 1245 and an engine power of 1200 (the best engine i have)
i didnt build this thing because i couldnt, but i build medium tanks instead.
they cost only ~3500 oil and use ~50 oil per hex. cheers....

the tanks have an engine design of 86, weight 1120 and engine power 800.