Maybe someone has the answer to this situation. I notice when I set the cruise at about 70 mph (1850 rpm), my pyro reads 750-800. When I raise the cruise speed to 75 mph (1950 rpm) the pyro reads 650-700. These are all level ground no-load situations. I know the higher rpms and thus airflow will carry away the heat faster, but am I getting the same mpg?