Yeah I have heard failure stories, but have had good luck w/ mine. The cars are strictly street driven. A Lotus Esprit Turbo and a 1st Gen Mazda RX-7 w/ the rotary. Most miles are on the Lotus and it has operated fine since I purchased the pump in 2004. It has been driven quite a bit and as often as possible in the winter, weather/salt permitting. It has no thermostat (runs way to cold), but w/ the success of the Mazda coming up to the proper temp and continually recirculating w/ the external bypass stat, I will fit one to the Lotus. No hot spots and I get great heat too.
Just found this from the website: (Note the pump is used w/ the Davies Craig controller)
"Question No. 9
Will the fitment of an Electric Water Pump be a drain on my electrical system?
The extra current is very little. About 90% of total motoring time the EWP will run at 10% of its maximum speed using about 2 amps. Being in nylon, the impeller can have aerofoil cross section and the tip clearances can be very small. A mechanical pump has to perform at 600 rpm and 6,000 rpm and it cannot be efficient at both these speeds and all speeds in between. Furthermore, as the power the pump requires to operate increases as the cube of the speed - when the mechanical pump is operating at the higher speeds, as it does, as a car passes through its gear range, its ‘robbing’ engine power in the order of 6 to 10kW. The EWP® which uses at maximum speed 9 amps x 13 volts gives 120 watts at say 30% efficiency from the alternator to hydraulic power means about 0.4 kW to drive the EWP®, when it does operate at full speed."