If you put hot water in a coffee maker instead of cold will the coffee be extra hot when finished?

This technique makes the resultant cup less bitter if used in a moka pot coffee maker. It has no impact on temperature of the brewed cup. This is specific to the moka pot brewing method.

Low cost coffee makers ie drip or lifter machines use a lot of plastics and cheap thermostats operating just below the boiling point of water.

Results may vary across different makes but we have our doubts if it will make more than a couple of degrees difference. You may risk damaging the plastic parts in cold water path though. So the bottom line is we do NOT recommend this process for any automated coffee makers.