Ahhh which brings us to the correct use and interpretation of the Cessna Economy Mixture Indicator the correct use of which enabled one in any particular type, to trade say 3% of speed for up to increase in range of 15%.
You got the choice between Best Power, (max speed) thru Recommended Lean to Best Economy.
I also wonder how many power computers are still out there and in regular use. How else does one set a % power in order to achieve flight planned KIAS and Fuel consumption?? Or indeed work out exactly what power you are getting.