On my Garmin 265WT unit, I have found that the eco Route challenge score can be changed by adjusting the city and highway mileage values in the Vehicle Profile screen. Apparently, 99 is the highest score you can achieve. I am trying to adjust the settings such that when I am driving 50 mph, the Eco Score will read 99, as that speed is when my torque convertor just locks up and gives me the best mix of gas mileage and trip time. I don't care if the cost per mile and mileage reports are inaccurate by biasing the city and highway numbers. Does anyone know what algorithm is used, so I can zero in on this adjustment , without trying a load of random numbers?