Is this correct?

Reply Subscribe

Thread Tools

Search this Thread

Jul 21, 2011 | 08:40 AM

Magnifico

Thread Starter

Driver School Candidate

Joined: Jul 2011

Posts: 1

Likes: 0

From: Montenegro

Is this correct?

Hello everybody,I am driving Lexus GS 300 (Europe).
I am wondering is it correctly to get in from D mode to N mode on every traffic-light or downhill or straight road because of,so-called fuel saving?I think it can damage automatic transmission but I am not sure..advance grateful for advice.

Jul 21, 2011 | 08:45 AM

rominl

exclusive matchup

iTrader: (4)

Joined: May 2002

Posts: 81,915

Likes: 512

From: Lovely OC

i don't think it save any fuel, or at least it's so marginal.

but i think the main idea is safety, because there is no momentum to move forward and it's just about slope and brakes. i know in some asia region (where i come from, at least), when you do your road test, every stop, you need to throw tranny in neutral. i don't think it will hurt your tranny

Jul 21, 2011 | 10:00 AM

worker

Lexus Champion

Joined: Aug 2009

Posts: 2,080

Likes: 6

From: of insanity

Well... the RPM is higher in N than in D at a dead stop. So if RPM = fuel burn than N would burn more fuel than D.

Jul 21, 2011 | 10:36 AM

rominl

exclusive matchup

iTrader: (4)

Joined: May 2002

Posts: 81,915

Likes: 512

From: Lovely OC

umm, interesting question, i don't know exactly how it works. but in neutral, the load is less too i think, so i would think it's "easier" to raise the rpm. but either case, i can't see N or D making real world difference in fuel consumption (when stopped)

Jul 21, 2011 | 11:00 AM

designo

Lead Lap

iTrader: (6)

Joined: Sep 2009

Posts: 3,506

Likes: 514

From: Bahrain

It is sometimes recommended to drop your gear into N at a long stop. Mainly due to gear load. But it's not absolutely necessary.

As far as fuel consumption is concerned, yes.. if your vehicle is rolling and you drop into N, your revs will fall and save fuel.

However, if you put it into D while still rolling is not a good idea. Your transmission in most cases will not match your engine speed accurately and you will hear a "clunk". If you do this frequently, you risk damaging your transmission gears.

Jul 21, 2011 | 11:15 AM

worker

Lexus Champion

Joined: Aug 2009

Posts: 2,080

Likes: 6

From: of insanity

Quote:

Originally Posted by rominl

is RPM the number of revolution of the Crankshaft? And the crankshaft is push by the piston which ... fuel related. So remove the load cause the crankshaft to move faster which cause the piston to fire a little faster too... which result in a bit more fuel burning.

Anyway, stick with D. The only time I roll with N is when I don't want to start my engine down hill for a short distance.

Jul 21, 2011 | 11:39 AM

rominl

exclusive matchup

iTrader: (4)

Joined: May 2002

Posts: 81,915

Likes: 512

From: Lovely OC

Quote:

Originally Posted by worker

i don't know, but if you consider engine braking on a downhill, you use lower gear and rpm is high, but that doesn't burn more fuel. but yes, this is kind of OT.

for me i just keep it in D