We have a Disco 2 2003 V8 automatic thats extremely heavy on fuel. Any tips on how to improve fuel consumption?

 

Make sure everything is tip top. Plugs, wires, filters, and O2's. Proper tire inflation too. Probably won't help much but running synthetic gear oil in the diffs and transfer may help a little.

Aside from that, select PARK, key off.

 

Also check with your code scanner or other device to see that ECU is placing the system into "closed loop" where fuel is controlled by constant updates from sensors. In "open loop" it assumes some default parameters and will run very rich. A defective sensor can instruct the ECU to do this, and the ECU may do it without a code being set. The O2s are the main control as Higgs mentioned, but in "open loop" they can be ignored by the ECU if it thinks other conditions exist (like very cold outside air, etc.).

 

SLOW DOWN!!!!

I went from 12.5mpg at 65mph to 16mpg at 60mph.
End of story, next question, if you are not willing to slow down then dont complain.
I'm not saying you have to drive 60mph, I'm just saying slow down from what you are driving.

 

Lol, what are you getting for gas mileage