Lady, just knock it off already.

[ADeMartino]

How's that supposed to work if you're sitting in bumper-to-bumper rush-hour traffic where you might sit for 2-3 minutes, move a few feet, sit for another 2-3 minutes? Seems like constantly stopping and re-starting the car would be worse. Not to mention pissing off the people behind you.

The debate over 'let it idle versus shut it off' first originated in the oil embargo of the early 1970s. Someone actually did the hard research and concluded that it was more fuel-efficient to let the engine idle for 4-5 minutes than it was to shut it off and restart it.

But you have to remember the vast differences, technically speaking, between that vintage tin and modern cars. The majority of cars of the early 1970s were large, heavy, and had carbureted V8 engines. Even the 'economy' models had six-cylinder engines.

Modern engines are fuel injected, computer-managed, and far more efficient, and the techniques that worked for the old land barges aren't necessarily the best for modern vehicles.

Hypermilers (people obsessed with fuel economy) claim that it's different than it was - that it IS now more fuel-efficient to shut the engine off if you plan to let it idle more than a minute or so. The key word there being 'plan'. For instance, if you're stuck at a particularly long traffic light, or if, like the OP, you are idling the engine for heat. Obviously, there are other concerns as well - and rush hour is annoying enough without fiddling with the ignition switch, yeah?