Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Does turning off engine at red lights save gasoline?

So there’s this annoying red light on my way to work. When the light turns red, it is one minute and twenty seconds until it turns green again (I timed it). So if I am the first or second person at the light, I put the car in neutral and turn off the ignition.

Will this in fact save any gas? Are there any other downsides to doing this? My wife claims it’s dangerous (it is not a dangerous neighborhood).

So am I saving any gas, or am I taking this “green” thing too far?

Thanks in advance,

– Mark

Down sides.

  1. You annoy me when you don’t get moving quickly when the light changes.
  2. Added wear on your starter, battery, and alternator.
  3. Spousal discontent.

Saving gas?
Probably not. It takes more gas to start an engine than while it is running. It will also have to work a little harder to recharge the battery. Clearly, there is some break even point for your specific car where the overall gas consumption will be less, and it is dependent on how long the engine is off. I don’t know where that point is, and it might be as little as the one minute that you are stopped.

Hey Mark,

Well the potential fuel savings are off-set by the disadvantages that tardis mentioned. It’s rare for me to even put my car in park, such as while waiting for a train to pass and it’s more rare than a blue moon for me to feel compelled to shut down the engine. Maybe I will if the thing is just barely crawling along, but again, it’s rare.

I used to have a pizza gig and I would almost always leave the engine running while at the customer’s front door.

Doing regular preventative maintenance on your car will go a much longer way toward being green.

Hope that helps.

If we were talking about a car from the 1970s with a carburetor, there would be no fuel savings from shutting it off for 120 seconds. However, with today’s fuel injected cars, if you are going to leave it on for more than 60 seconds, you can save fuel by shutting it off. However, saving fuel shouldn’t be your only concern.

How much fuel will you save? I don’t know. Is it worth the extra wear and tear on your starter? Not in my opinion.

Think about carjacking. If you are first in line, and your car is approached by a carjacker, you have the option of running the red light, but only if your car is already running. Even if you are not first in line, having the car running might allow you to escape faster.

At truck driving school and the Motorcycle Safety Foundation’s Basic Rider’s Course, we were taught there is a remote chance that being in gear ready to go can give you a safety advantage. Even if the chances of you reaping any benefit are remote, I think it is still a good idea to leave it running.

If you are so obsessed about saving fuel, buy a moped.

With a modern engine the break even point for leaving the engine running vs. shutting it off and restarting is less than 20 seconds,.

Yes, it saves fuel. That’s why some hybrid vehicles shut off their engines while at rest. I don’t think it’s dangerous. I believe this is common practice in parts of Europe where fuel is expensive.

It doesn’t save a lot of gas, but every little bit helps.

Those hybrids also have special starters that are more robust than normal starters, so they can stand up to the extra use.

It saves an amount too small to measure, but IMHO it truely is not worth the added wear on the starting system. McP correctly pointed out that hybrids do this, but their starters are designed to survive routine cyling to a greater extent than yours is.

But unless you live in an urban area, where slow starting from a light can earn you a crowbar on the skull, it isn’t dangerous. Much of the difference in the responses you’ll get is truely philosophical. Some feel that every drop saved is important, some do not. I’m in the latter group.

Yes it does, depending on how long.
Unless you have a golf cart or hybrid that was designed for it, it isn’t worth it to shut down unless for it’s for extended waits .
Yes it may be dangerous in some situations as you can imagine.
So bottom line, like in most discussions, there are different sides when you look at ALL the factors involved including length of time and technology in your vehicle.

The extra wear and tear on the starter and iginiton switch will eat up any savings you might have from shutting off the engine at a red light.

Like others, I shut the engine off when waiting for one of those long freight trains to pass.

You may cause an accident by annoying drivers behind you who expect you to get moving as soon as the light changes.

While I won’t turn the motor off at every stop light, some are ridiculously long. When I visit my son in Wilmington, NC I notice how long some of the lights take to turn. If I lived in Wilmington NC I likely would kill the motor on some known long lights.

This seems to be the case here, a 1 min. 20 sec. light seems like a long time. My car restarts very quickly and I won’t hold up the traffic behind me so in this case I go along with the OP and kill the motor.

It definately saves thimble full of gas, but it adds up if done by lots of cars. I haven’t replaced a starter in a long time so I’d risk the wear and tear on the starter to save some gas.

Today I turned my car off at the drive up bank window, so it is something I’ll probably be doing more often in the future.

Why a moped? Why not a bicycle?

Does it save gas? Yes.

Is the reduction in gas consumption significant? No.

The few pennies that you are likely to save each week will never add up to the cost of just one new starter and the labor to install it.

Save gas? Yes a small amount. My guess is that if you already have one or when you get a car with an oil change computer feature, the savings will be offset by more frequent oil changes as well as other things mentioned. Engine starts are part of what the program considers. Cold starts count for more than hot starts.

Yea, you might save a gallon a year, but you would need to replace the starter about every year also. UNLESS you had one of those SUPER starters that someone said that the hybrids have.

Oh come on…
I’m against this whole shut down at the red light thing, but to say that it will cause the OP to have to replace the starter every year is silly. He’s talking about two extra start cycles per day. I don’t think that’s going to make that much difference in starter life.

I believe the point was that while you may save a little fuel, it will likely cost you more in the long run. The difference is not enough to worry about either way.

The OP is talking about one or two extra starts per day.

Two cycles fine…but let OP continue shutting off his car on a more regular basis…and regardless, I wouldn’t buy one used if I knew the previous driver felt that way and did it.
Just another excuse for the guy/gal behind you to blow his/her horn.

So, Tardis, he’s talking about four start cycles vs. two start cycles per day. Could one then conclude that the starter life would be reduced by 1/2? Of, if he stops for supper every day, 1/3?

I’ll stand by my belief that the gas saved isn’t worth the extra wear on the starter.