[thorpie]

Hello Bob
The y values for each contour are separate columns. The curve # values separates them into columns.
The consumption lines in the second chart are actually contours, they just end up squashed flat.
Their y values are calculated in the cells starting in column AA.
These values are calculated as KwGross/SpeedKmh*BSFCinGrams/1000*0.74*100).
As in 1 hour @ 100 km/hr @ 50 kw gross = usage of 50kwh/100 km and 1 kwh = BSFCinKg/0.74 kg/litre fuel weight.
The theoretic minimum fuel consumption would be a curve joining the end points of the lines.
The code that calculates speed from power input is in the macro module. Please feel free to use that elsewhere. It needs to solve a quartic (power 4) equation and is a pain to have to recreate.