[shanghaining]

I've heard different opinion about this, but usually when I drive, I often put it into neutral when I roll into a red light, or sometimes going down hill, because of the low RPM at idle rate, naturally I'd figure it save you gas. But I heard that putting your car into neutral acutally takes more gas then in gear? Because they say the engine uses gas to make the RPM a certain rate?

Anyone have any comment or suggestions about this?

What is the best way to save gas besides shifting early?/

 

[ComposiMo]

For all practical purposes, i doubt you'd see any discernable difference between the two, and what you DO see, would be wiped out with one flooring of the go-pedal to get out into traffic....

Think of it like this though... its easier (and cheaper) to change the brakes than it is to change the clutch. Downshifting and so forth to slow the car down only causes the clutch to engage that many more times, causing the clutch to wear out faster than it would if you just put it in neutral, and used the brakes only to stop the car.

Naturally, downshifting is more fun, so when driving a manual car, i do that anyway regardless of clutch wear... so whatever. lol!

 

[bobski]

Fuel consumption wise, coasting in gear will use less fuel. The ECU cuts off the fuel supply all together when coasting over 1500 rpm (or around there). But when coasting in gear, there's extra drag - compression braking. So I guess if you're coasting to a stop, leave it in gear.
If you're coasting down a hill, putting it in neutral will let you pick up some speed, but whether that speed is worth it in terms of fuel used by the idling engine, I don't know.

 

[jmart]

Just rev match on the downshift, then use the engine's compression for additional braking, and to save gas. THen you won't wear out the clutch so you'll be saving gas money and brake pad money!!!

 

[Charlie]

so... when i downshift (to slow down) to 3rd at 45 and the engine spins up to like 4500 rpm im actually using less gas than when its in neutral?

 

[dohcrxl]

Downshifting to slow the car to me is a total waste of time and money even if you rev match. No one in the world can rev match perfectly everytime. I've been driving big trucks for 500 thousand miles where you have to rev match on every upshift and downshift and I still can't do it perfectly everytime. And for everytime it's not perfect, the clutch is wearing away needlessly. Not only that, so are the synchros in your tranny.

Not only that, 4500 rpm's in 3rd gear versus 800 rpm's in neutral means there are THREE THOUSAND SEVEN HUNDRED more times per minute where the piston rings are scraping up and down the cylinder walls. That many more times that the waterpump, oil pump, entire valve train, gears in the transmission are spinning creating additional and uneccessary wear.

Engine braking is only neccessary when your vehicle weighs 30 thousand pounds or more and you are going down a steep mountain grade. Other than that, I think it's silly. (unless someone can list the benefits)

 

[Charlie]

Downshifting to slow the car to me is a total waste of time and money even if you rev match. No one in the world can rev match perfectly everytime. I've been driving big trucks for 500 thousand miles where you have to rev match on every upshift and downshift and I still can't do it perfectly everytime. And for everytime it's not perfect, the clutch is wearing away needlessly. Not only that, so are the synchros in your tranny.

Not only that, 4500 rpm's in 3rd gear versus 800 rpm's in neutral means there are THREE THOUSAND SEVEN HUNDRED more times per minute where the piston rings are scraping up and down the cylinder walls. That many more times that the waterpump, oil pump, entire valve train, gears in the transmission are spinning creating additional and uneccessary wear.

Engine braking is only neccessary when your vehicle weighs 30 thousand pounds or more and you are going down a steep mountain grade. Other than that, I think it's silly. (unless someone can list the benefits)

it sounds awesome 8)

 

[Paul]

i personaly dont downshift

i really see no point in it but thats just me

 

[shanghaining]

thanks for the info,

say when you drive and you see a red light far ahead, you are currently in 5th gear going 40mph, when you see that light you decide to put it to neutral and let the car roll to that stop. Does that uses less gas as oppose to keep cruising at 5th gear and stop then put into neutral?

 

[bobski]

3. Fuel Cut-off Control
• During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at speeds over 1,300 rpm (Std.), 1,100 rpm (HF) or 950 rpm (Si).

Ok, so I was a little off. In the above situation, you are using no fuel. None. None is less than the little bit it takes to idle the engine. So you would be using more fuel by putting the transmission in neutral or pushing the clutch in - the engine speed would drop and it would start using fuel to idle.

 

[shanghaining]

So the best way to get best fuel economy is to put it in neutral at the last second?

Hahhah, I wonder if I can acutally see the difference between mpg. Prabably not since I rev it really high, and gun the petal. :roll:

 

[dohcya]

It's an HF, no need to be gunning the pedal lol =)

Givin' ya a hard time =)

 

[SETI20]

Rev-matching is less jerkey and thus more comfortable. Especially with my sports-like clutch.
...there's your benefit.

 

[dohcya]

i too am a big fan of rev matching. not only is it easier to slow down but it is also great to use when passing someone or just wanting to mash the pedal some...

 

[akirarex]

Yes it would be more fuel efficient to remain in 5th until you had to shift into neutral at the last second just to keep the engine running. Then when it's in neutral it will do the o2 dance for catalyst reasons. What about when you are sitting at a light, do you keep your foot on the brake pedal????

If you use a lightweight flywheel engine braking is noticabley more effective, and way more fun.

 

[shanghaining]

mine is a DX!!!!!!!!!!! :wink:

 

[dohcrxl]

Rev-matching is less jerkey and thus more comfortable. Especially with my sports-like clutch.
...there's your benefit.

I asked for benefits, plural and obviously enough to out weigh the cost of...

Additional clutch and synchro wear, 3700 more scrapes (as per above example) of the piston rings up and down the cylinder walls, that many more times that the waterpump, oil pump, entire valve train, gears in the tranny are spinning creating additional and uneccessary wear...

just so there's a more comfortable shift? and of course you save on brake pad, whooo hooo. It's more than counter-productive but hey if you've gotta have the fun/comfort factor then it's worth it right?

 

[jmart]

Another reason I think I downshift through the gears on decel is because I also ride a motorcycle. On a bike, on the street, you always want to be in a gear that puts you in a a decently powerful part of the the rpm band at a given speed so that you can quickly do evasive maneuvers when some dip**** in a cage cuts you off or tries to run you over. This may or may not be necessary with the crx.

 

[akirarex]

I have found that you are more noticeable on a bike than in a crx.
On a bike it's a must to stay in the power band, you may feel the same about a crx too.

 

[7PSI CRX]

3. Fuel Cut-off Control
• During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at speeds over 1,300 rpm (Std.), 1,100 rpm (HF) or 950 rpm (Si).

If the above were true.......

The car would not, could not

backfire.

My car used to backfire on dececeration.

Anyone want to explain to me what was burning?