1) I know how much fuel my tanks hold (usable) since I've run them dry
to find out.  One needs to do this in flight to find out.

2)  I have verified that my rate of burn is very accurate.  It will
result in less than 1/2 gallon difference at any fill up.

3) I always plan a one hour reserve.  I don't know too many pilots who
would chide me as being risky on that count.

4) My on-board totalizer is very accurate.

5) I know within a 1/2 gallon how much fuel is on board before I start
the flight.

6)  I can check that the fuel burn IS what I think it is by running
tanks dry.

7)  I cannot recall a flight in the last ten years where the fuel
remaining at landing was more than one gallon different than I
calculated it would be.

Walter, Et Al

 

I almost agree with you completely -

 

Cars - I do know the fuel burn in each because they either have a fuel computer and/or the trip odometer is reset at each fill up.

 

Motorcycle - No gauge, after the yellow light comes on I've got 20 - 40 miles to find a gas station, depending.  The trip meter is crucial.

 

Airplane -

 

For planning purposes I make the conservative estimate of 10 gal per hour, 3.5 hours betwixt stops, no wind, with 8 gallons left if I have filled the tanks to their 43 gallon capacity (1/2 inch below the lip).  Once in flight, time remaining at the present flow is compared against en route time as calculated by GPS.  I don't have to land at the planned site and 3.5 hours is my personal sit time limit.  An example of change was a flight from Chicago to Tampa (normally about 5.5 hrs, stop in GA for fuel) flown at 9500 MSL, with a 40-50 Kt tailwind and LOP meant I landed at Tampa in a little under 4 hours with 13 gallons remaining.

 

I know this.  My wings can be drained (pumped to header) in level flight down to 1 cup unusable fuel.  My carefully baffled header has been flown under normal maneuvers to 2 gallons remaining.  By design, it could probably go to 1/2 gallon under coordinated maneuvers.

 

I make it a contest to estimate the fill-up requirement although the EPI 800 system has not been off by more than one gallon.  The on-board totalizer is very accurate but is always slightly off by claiming I used more gas than I did.  The tank probes are very accurate except that, by design, the gauge indicates zero at less than 2 gallons in any tank.  It's OK because an idiot light comes on when the header hits 2 gallons.  My automatic system pumps from both wings to keep the header within 1 gal of full.

 

The only time I got nervous was a flight around the east side of a storm (not the brightest idea) and down to 4 gallons remaining.  Hey, that's what the reserve is for.  BTW, ATC was suggesting slower planes (like C172) land rather than try to beat the storm.