Does Turning Your Car Off At Traffic Lights Save Gas? KNDU Asks a Mechanic - NBC Right Now/KNDO/KNDU Tri-Cities, Yakima, WA |

Does Turning Your Car Off At Traffic Lights Save Gas? KNDU Asks a Mechanic

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KENNEWICK, Wash.--  Everyone is trying to save money on gas these days.  There have always been questions as to whether turning your car off at traffic lights or drive thrus saves gas or not.

Today two mechanics agreed that it depends how long you're going to be stopped.  

Today, KNDU polled some drivers about what they thought saved more gas, idling your car while stopped, or turning it off then back on.  Most drivers guessed just leaving your car on at a light is probably be the best option.   Kenny Gorsline guessed, "It probably takes more gas to turn it off and start it back up than it does to just leave it running."  Ben Clark guessed, "I would say keep it running.  Otherwise, you're going to put a lot of wear on your starter and drain your battery.  You're in trouble if you can't get it started again and you have a line of traffic behind you all honking their horns."

Gorsline also questions the safety issues of turning your car off at an intersection.  He says, "At a light, I think it's a safety issue that you should leave your car running."  If you turned your car off and it wouldn't turn back on, you could hold up traffic or even cause an accident.

Only one person thought she should turn it off.  Olga Rodriguez guessed, "I don't know if it'll make a difference, what I'm saving or not, but I usually turn it off."

After all the guesses, KNDU talked to a mechanic.  The general manager at Jiffy Lube, Destin Boyd, says it's better to keep your engine running.  Boyd says, "I think it's probably going to take more gas to start your car than it is to actually sit at an idle."  So if you're at a traffic light or drive thru, he says keep it on, but, "if you're at a long stoplight or a long train, it's probably better to turn your car off and have it sit than have it sit there and run gas."

Boyd says your engine has to work harder to turn back on, than to keep running for just a few minutes. Boyd explains, "When you go to turn your key on, your fuel pump is going to engage, and it's going to shoot gas into your system, which is going to spark.  When you're at a constant start, your car is at a constant idle so it's constantly pumping gas through your system.   It's only using a certain amount.   So when you go to start it, it's going to take a little more [gas] to start it than to actually run the car."

Boyd also added that older cars use more gas to start than newer cars.