what's more energy efficient? idling or turning off and restarting your car

If you ever wondered this, here's the answer:
(thanks SustainLane's Greenbusters!)

Idle Cars are the Devil's Playground

Myth: It takes more energy to restart a car than it does to leave it idling.

Conclusion: BUSTED.

Truth: For every two minutes a car idles, it uses the same amount of gasoline it takes to travel one mile, says the California Energy Commission (CEC). More than ten seconds of idling uses more fuel than restarting the engine.
Bottom line? Turn your car off.
More idling related tips from the CEC:

• Idling is not an effective way to warm up your car. Driving the vehicle is the best way to do this.
• Excessive idling can actually harm your car. Fuel residues build up on cylinder walls, damaging engine components and increasing fuel consumption.
• Some people mistakenly believe that continually restarting their cars will lead to excessive wear on the battery and starter motor. Wear adds about $10 a year to the cost of driving, which is less than the extra cost of gas your car likely uses when idling.