Turning off my car at stoplights-should I do it?

Dear Tom and Ray,

We own a 2004 Honda Insight hybrid and, as you know, one way in which this car achieves its superior fuel economy is that the combustion engine turns off whenever the car comes to a stop. Our other car is a Subaru Outback, which gets half the fuel economy as the Insight, but we love it anyway. We happen to live in a city that has painfully long red lights lasting between 3 and 4 minutes, during which time we waste gas, money, and our lives. I have proposed to my wife that we could save at least the gas and money by turning off our Subaru while stopped, then quickly turning it on again just before the light turns green. Although good in theory, we were wondering a few things:

1) Would we actually save gas using this method? I’ve heard that starting up the car uses more gas than when the car is just idling.

2) Will repeatedly stopping and starting the car damage it in any way?

3) Must cars be hybrids to utilize the autostopping technology?

4) Is there anything else we haven’t considered?

Thanks for all of your advice over the years.



St. Louis, MO

That’s a lot of extra wear on your starter. It probably wasn’t designed for that.

Yes, you will save some gas. An idling engine burns fuel. An engine turned off does not. It does not take extra fuel to restart the engine.

You will cause extra wear to the starter.

There may be a safety issue. If you had to move the car quickly in an emergency there would be a delay while you restarted it.

Don’t bother.

If you wanted to send an email to Tom & Ray you chose the wrong link.


Whatever small amount of money that you might save on gas will be offset (and likely exceeded) by the cost of replacing that expensive starter prematurely.

I think it is a bad idea.

3)no, but there would be problems with this
4)you might miss the AC/heat, safety might be an issue, slow startup might cause some road rage

Wes Sprinkle

It’s another waste of time.
Now instead of just pushing on the gas when the light turns green, you have to pay close attention to the cycle by observing the opposing light to time it just right. Whereas you could just sit and enjoy your music in peace.
If you are not in the first few cars in line you miss this and cause a delay in the line of traffic behind you. At the rear of which at least two cars now MISS the green light and need to wait again for the next one wasting THEIR fuel and time.

As a parts man , I’ll be glad to sell you at least two more starters over the life of the car than you would otherwise have needed. cha-ching.

One part of the equation you’re missing is this: A 2004 insight weighs between 1,800 and 1,900 lbs. Turning off the engine at stoplights, for all the aggravation, starter wear, and above mentioned safety issues, will not save you that much gas. Subaru Outbacks weigh 3,400 lbs. and change, plus there is the extra mechanical friction from the AWD system. Hybrid or not, the Insight would not get the mileage that it does if it weighed as much as a real car! Non-hybrids do not have starter motors that are designed to constantly re-start the engine as a hybrid does.

No dont do it…it isnt worth burning up your starter with so many extra starting cycles…it would save some fuel however…but not enough to offset the starter replacements.

Now…in the future we may see this incorporated in production cars…IF and or WHEN they do this they will have a more robust starting system in the vehicle NOT the conventional starters we have today. They would probably use an electric motor just like the Hybrid vehicles use…this electric motor will be far stronger and engage the engine in a different way than our conventional starters do…so it wouldnt matter how many x the hybrid system restarted the engine…it wouldnt hurt the motor.

They do this on some Hybrids now…but the restarting is done with that other electric motor.

dont do it

Everybody stated its hard on the starter and thats true. It’s also unsafe.

For the 2012 or '13 model year, Ford will be bringing it’s start-stop technology that’s popular in Europe to the US. It’ll automatically stop the engine then restart it once you need to get going. Buy one of those models when it comes out.

When you roll up to a red light, how do you know how long it’s been red? I would suggest you turn off your engine at stop signs.

No question,engine off for a four minute red light.