Takes 5 min. of research to find that it's better to drive slowly than to idle to heat up a car. I read a study GM did in the 80s. That was the result. (even in cold climate where you want cabin heat; that doesn't build fast at 6hp (idle) your much better off driving.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)