[Synchro909]

I figure that the gauge is most needed when the fuel is low so I set mine to read empty when the float is on the bottom of the tank. When that happens, I know I am low on juice and I'd better do something about it. If I push my luck, I can still get an idea of what's happening in there by swerving the car and watching to see if the guage moves. Any splash of fuel in there will cause it to move slightly. If I get no movement, I get ready for a walk!
When the tank is full, I can see the fuel in the glass so the guage is redundant. In my earlier cars (smaller tank) I allow 200 miles per fill with some in reserve. When we are outback and towing the camper (which weighs about the same as the car - about a tonne), I allow 200 km. ANY mechanical fuel guage is only an indication of how much fuel you have. After that, it's about knowing your car, IMO.