How to find Maximum of a value between two overlaying contour plots?

I have an engine plot which has Torque on y axis and the Engine speed on x axis. I have overlaying contour plots for Engine Power (0-75) and Engine Efficiency(0.2-0.4).

I would like to find the maximum value of efficiency at each value of power. For eg. for power of 10 kW I want the maximum value of efficiency (between 0.4 to 0.2)

Then save each of this maximum efficiency value (as an array) and super impose on the same graph so that i have a curve which shows maximum efficiency at each power value. Does matlab have something in-built such that it shows a curve which will fit this requirement?