Discussion: Will putting your car in neutral actually save gas?

"Weaponsboy: your argument is flawed: If running the engine at the same speed always yielded the same fuel economy, how do you explain that a fully loaded car gets a lower mpg than an empty one?"

"I have a standard transmision in my truck so puting it in nutral at a stop light will save the clutch throwout bearing. but not any noticable amount of fuel. I have gotten pretty good at judgeing the length of a traffic light more than five seconds turn of the motor and watch for the light next to yours to turn yellow for the restart. saves a little bit
The big saveings from a standard trans comes from shifting into nutral on long hills and letting gravity do the work I leave the engine running for brakes and power steering but at engine idle the fuel savings are huge. The more RPMs the more fuel you burn short shifting and coasting wereever posible can increase your fuel milage. Automatics not so much.
However one fuel saving tip for automatics is shut off the overdrive at low speeds. The reason for this is the torque converter lock up speed is set to engine RPMs without the torque converter locked 15% of the engines power is wasted. So the higher gear keeps the engine speed low but doesn't lock the converter. It takes some time to figure out the lock up speeds on the varios vehicals most of the time it feels like the trans just found another gear when the converter locks. If you feel 5 shift points on a 3speed auto with over drive the last one is the torque converter locking."

"I still feel the wear & tear on the starter will be more expensive than the gas. Especially for my drive. I hit several dozen lights each day."

""Your next car should be a Prius "
Let me know when they build a full size pickup with trailer towing capability and I'll be at the dealership next day."

"Perhaps the real question here is "Exactly how much does it really save?". Unless you are talking stop and go driving and stop signs at every corner for your entire commute, putting the car in neutral is more a pain than what it saves you. Frankly, I have better use of my time than farting around with shifting gears when I am on the go. This is much like counting pennies and then forgetting the dollars going out the window. My suspicion is that the extra wear and tear on transmission and clutch (both manual and automatic) are not worth this kind of horsing around. For the AVERAGE motorist, if you want to save gas (and that is your be all and end all) than buy a lighter weight car and smaller more efficient engine. Basically, if you feel you "need" a full size pickup with towing capability, just suck it up and pay the enormous gasoline bill, there is isn't really much hope for you.

And to those who think electric vehicles are the answer, remember that the electricity to charge your batteries must come from someplace. Unless you live in an area with wind, solar, hydro, or nuclear, you are not doing much for the carbon footprint. In most areas of the U.S., we generate electricity from fossil fuels. So you have a choice, pollute at the end of your exhaust pipe or at some distant power plant. I do get a kick out of the movie stars who drive the electrics and claim they are not polluting, tell that to the people who live in Four Corners!"

"I would love to see someone do some cold hard un-biased testing to see what the break-even point is on letting the engine idle versus turning it off and then hitting the starter again. As I understand it, most cars use a little bit more gas starting up than at idle. And don't forget that it takes electricity to run the starter. That means you have to recharge the battery via the alternator/generator and thus pull more power from the engine and so burn more fuel.

As for the fly-wheel starter, it still requires energy to spin it back up to speed and it also means that you have to drag around extra weight all the time. More mass to accelerate means it will take more energy to do it.

Bottom line is that it will take more consumer demand and we in America have been programmed into a bigger-is-better mind-set. Every day on my way to work I see single 110 lb drivers being carried down the highway at 85 MPH by 9500 lb., V8/10 gas guzzling monsters. They're not pulling trailers, moving construction equipment or transporting a college football team. They're carrying the 105 lb Mrs. and 25 lbs of groceries. Seriously, they could get the job done with a Smart car or VW bug. Who really needs a Denali or a Hummer to drive around town?"