The block heater seems to be able to maintain a temperature of 40 F regardless of how long you leave it plugged in, well at least with temps not exceeding 40 F from my experience. Why didn't they design one that can maintain the coolant at a temperature closer to the optimum operating temperature (80 F)? I mean, I know it will draw more current, but I just think that engine wear would be reduced even much more if the engine and coolant (and oil) were closer to operating temperature when you start the car. Afterall, isn't the expansion of the cylinder walls and other engine components during cold starts the greatest source of engine wear?

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver