My knowledge of the German language is essentially nil. However, I would think that the left side of the y-axis graph below refers to Horsepower and the righthand side refers to torque. The x-axis is obviously RPM.
From the K75 power/torque graph below, would the lowest fuel consumption occur at the 4500-4600 rpm or where the torque and power curve intersect? Also, is there something to be interpretted from the 6750-6900 rpm range where the delta between torque and horsepower increases? Is that the point where one gets the maximum from the K75 engine per unit of fuel?