[ecomodded]

Sample size were small. Ridiculously small.
Not a good way to measure fuel economy.
Even if the fuel was supplied from a portable fuel container, either incrementally marked or placed on a accurate weigh scale, 30 miles is just not enough run time to get effective comparable results with.
Just using the cars gas tank and the auto shut off at the gas station after 300 miles let along 30 miles would be inconclusive. The longer the sample mileage the more complete of a result you will get.

The cars gas tank should be filled from the same pump, parked in the same position and filled to a point on the filler hoses neck where you can see the settled non foamy gas's level, repeat on subsequent fill ups.
Not trying to be Dic to you HydroJim, its how i measure my cars economy because its the only way to accurately measure at fill ups, short of supplying the gas to the car from a Jerry can.