Gallons Uncorrected miles corrected miles 7.7% corrected mpg Notes
14.1 193.4 208.3 14.8 lugging it
13.8 208.3 224.3 16.3  
13.85 190.3 205.0 14.8  
14.87 184.2 198.4 13.3  
14.3 202.4 218.0 15.2 mellow driving
14.1 208.4 224.4 15.9 semi mellow driving top up 3 days, no rear windows
13.9 177.9 191.6 13.8 mostly beatin' on it
13.1 173.5 186.9 14.3  
13.4 206.5 222.4 16.6 top up regular driving
12.7 201.7 217.2 17.1 top up regular driving
13.9 177.9 191.6 13.8 mostly beatin' on it
13.1 173.5 186.9 14.3  
13.4 206.5 222.4 16.6 top up regular driving
12.7 201.7 217.2 17.1 top up regular driving
12.9 180.4 194.3 15.1 mostly beatin' on it
12.3 163 175.6 14.3 mostly beatin' on it, rear seat out

It looks like driving with the top up is worth about 2mpg, but the sun and the wind is wroth more than that!

The 7.7% correction is based on an actual 70mph (gps) with an indicated 65mph. (70/65=1.077)