[dremd]

I think it is safe to say that an electric water pump on a thermostat will save energy on just about any ecodriven vehicle. BUT if you are operating in conditions which create lots of excess heat, then the mechanical pump will win out.
However the time for the pump to pay for itself is very long.

I had a short talk with a manufacturer of an electric cooling pump last week at SEMA ad they estimated that run time was between 5% and 20% on a SBC depending on conditions.