I bought this block heater to save on gas, reduce engine wear on cold starts and heat the car's cabin faster.Installed on my 2010 Ford Fusion. Works like it should. You will need a 14mm allen (hex) socket to remove the frost plug.I have the block heater plugged in a timer which starts about 3 hours before I need the car.At -20°C (-4°F), the use of a block heater can improve overall fuel economy by as much as 10 percent. In a test program conducted by Environment Canada, a vehicle sitting at -25°C (-13°F) was warmed using a block heater and then driven over a simulated urban driving cycle. This resulted in a 25 percent reduction in fuel consumption compared to cold-starting the vehicle and driving it over the same route.