You also have to be careful with block heaters.
I used the lower radiator block heater in my daily driver many years back. I would plug it in at night, and then in the morning if it snowed, I would start my car and by the time I had cleared all of the snow off of it, you could start feeling the heat coming out of the vents. It was nice, and helped minimize wear on the cylinders also.
HOWEVER, I go about paying my utility bills every month. (we're talking about Feb here.) Then come April/May, I get an electric bill for $1500.... WTF??? I was furious, how could I owe that much after paying my bill every month?
I call the electric co, and they inform me that the last three months they sent me an ESTIMATED bill. This is where they don't read your meter, but just bill you on your "average" rate of consumption....
Well, they finally came in April/May to read the meter and then sent me an ACTUAL bill for $1500....
Leaving my 750 watt block heater plugged in overnight ran up my electric bill....
So I put it on a timer after that where I would set it to turn the block heater on an hour to an hour and a half before I had to leave for work. Same end result for the heater output, but much less electric bill.....
FYI.....