I like block heaters, but I get the impression that the idea is a fading one... When we got our M-B C-240 my inquiries about available block heaters came up blank. I have one on the old Ford Ranger and also had on previous vehicles. It not only makes the engine start easier, but speeds the arrival of warm air for defrost and the heater. I like the idea that the engine gets a head-start on warming up, for a bit less wear n tear and less emissions too I expect.
If there's a block heater appropriate for the smart I'd be interested, as mine will be a short-range cross-town commuter this winter without much opportunity to get fully up to temp.