Drive to Neutral to Drive on HWY on AT, Safe?

[xxhaimbondxx]

OK, I had mixed stories on that form different people, so any professional advice from a pro would be appreciated. I like to drive on the hwy and if I go down hill, I just shift my AT to neutral and when I get to the bottom, I shift back to Drive again. It seems to me that this saves quite some gas, however, I was pointed out that it wouldn't be too healthy for a tranny to be shifted to Drive at high speeds. It doesn't look like tranny mind that I do that. I did that to my older cars and they were fine. What do you guys say?

[Fargone]

Doesn't letting off the gas completely make an auto act like it is in neutral ... which is why it doesn't engine break?? I always assumed it did.

If it doesn't, you'd be better off leaving it in gear, and use the momentum of your car to keep the engine running, instead of putting it in neutral and making the engine idle (which is bad for gas mileage). Which is what most people who drive stick do (for engine breaking).

[xxhaimbondxx]

Letting go the gas pedal doesn't do it for me, the RPM stay the same which does not benefit gas mileage, the car slows down faster than it was in neutral. Plus I don't understand how idling could be bad for gas mileage or break ur engine.

[Fargone]

Originally Posted by xxhaimbondxx

Letting go the gas pedal doesn't do it for me, the RPM stay the same which does not benefit gas mileage, the car slows down faster than it was in neutral. Plus I don't understand how idling could be bad for gas mileage or break ur engine.

I was spelling 'brake' wrong ... sorry

[Kakashi]

yes you can put the transmission into neutral and back into drive, but be careful, if youre going over 35-40 MPH you might want to rev the engine to match the RPM's so the synchros contact better.

heres my usual:

30-40: no revv

41-50: 3000 rpm

51-59: 3700 rpm

60-69: 4300 rpm

70+: 4700 rpm

just know this: the ECU reads what speed you are going before it decides what gear to put you back into. If you shift into D, 90% of the time it will put you in 5th gear and down shift accordingly from there.

You have about .5-1 second shift the car into the gear you want. If you take too much time to bring down the selector, the car will jerk from the tranny matching RPM.

Note: the R18 transmission also knows what RPM you will match to if you decide to downshift. If youre going 45 and try to downshift to 1st, it will not do it because it will blow the engine. It will not downshift for the most part if it will redline.

max downshift speeds that i find "safe":

5th- 69 mph
3rd- 55 mph
2nd-41 mph
1st- 31 mph

these speeds will provide engine braking if and when needed, as twistedframe has mentioned before, doing the stuff in red font probably messes up your tranny.

[audiophile]

Originally Posted by xxhaimbondxx

OK, I had mixed stories on that form different people, so any professional advice from a pro would be appreciated. I like to drive on the hwy and if I go down hill, I just shift my AT to neutral and when I get to the bottom, I shift back to Drive again. It seems to me that this saves quite some gas, however, I was pointed out that it wouldn't be too healthy for a tranny to be shifted to Drive at high speeds. It doesn't look like tranny mind that I do that. I did that to my older cars and they were fine. What do you guys say?

I do this nearly everyday... I've got about 30k on my car and no problems yet...

From my experience it seems as if the car puts it in the correct gear for me when I drop it back into Drive. Doesn't seem as if it causes any strain whatsoever on my drivetrain. I've never really experienced a "jerk" from dropping it back into D, no matter the speed. And I've done it going pretty fast too...

Nice to know I'm probably messin my car up...

If/when my tranny blows i'll let errbody know

[webby]

moved to the garage -

there was a big article on this subject in car and driver a while back and they showed that it actually lost gas mileage contrary to the rpms that you visibly see on the tach. Taking the car out of D and into N down a hill and back into D actually produced worse gas mileage and they said it would do more harm to the tranny over time. Keep it in D if you want to save gas, and it'll also save your tranny in the long run.

[dentrecords]

Originally Posted by webby

moved to the garage -

there was a big article on this subject in car and driver a while back and they showed that it actually lost gas mileage contrary to the rpms that you visibly see on the tach. Taking the car out of D and into N down a hill and back into D actually produced worse gas mileage and they said it would do more harm to the tranny over time. Keep it in D if you want to save gas, and it'll also save your tranny in the long run.

+1

Great info.

[Kakashi]

Originally Posted by webby

moved to the garage -

there was a big article on this subject in car and driver a while back and they showed that it actually lost gas mileage contrary to the rpms that you visibly see on the tach. Taking the car out of D and into N down a hill and back into D actually produced worse gas mileage and they said it would do more harm to the tranny over time. Keep it in D if you want to save gas, and it'll also save your tranny in the long run.

link?

[webby]

Originally Posted by Kakashi

link?

it was in the magazine - no link.

how to save gas -
Shift into neutral if you are not comfortable with downshifting. Standard transmission vehicles may save gas by shifting into neutral when going down hills steep enough to maintain speed (although engine braking is safer on steeper declines). Do not do this in a Hybrid car, they use this "regenerative engine braking" to generate electricity and charge the batteries. NOTE: This strategy will result in more wear and tear on your brakes. Neither of these strategies is recommended for normal automatic cars. Also, if you own a car with fuel injection, it is more efficient to keep the car in a high gear while going down hills. Simply take your foot off the gas.

http://www.wikihow.com/Save-Money-on-Gas

[Kakashi]

doesnt make alotta sense to me..

actually doesnt make any sense at all..

someone wanna chime in with a explanation?

[xxhaimbondxx]

Thanks for the info guys, however, I still got mixed answers.

[*007*civic]

Originally Posted by xxhaimbondxx

Thanks for the info guys, however, I still got mixed answers.

i do it all the time to.. doesnt make sence to me how u will save more gas if u keep it in drive.. my car usualy revs around 1900 in drive wen i dont have my foot on the gas and wen i put it in neutral drops down to 900.. i put it in neutral on the highway everytime i go downhill

[inline4]

^ because, when you take your foot off the gas and leave it in gear, ecm will turn off the fuel injectors and doesn't use any gas
put it into neutral, and it will need enough gas to maintain idle

[*007*civic]

thats interesting

[xxhaimbondxx]

interesting indeed. These couple of lines made more sense than everything else. However, in another post, guy claimes he traveled down hill from some place in Vegas to some other place, the road was down hill for 8 straight miles. He claimes that in gear it took twice as much gas as in neutral. He figured that out by attaching a computer to his car while driving it.

[*007*civic]

Originally Posted by xxhaimbondxx

interesting indeed. These couple of lines made more sense than everything else. However, in another post, guy claimes he traveled down hill from some place in Vegas to some other place, the road was down hill for 8 straight miles. He claimes that in gear it took twice as much gas as in neutral. He figured that out by attaching a computer to his car while driving it.

hmm... juss use ur cruise control lol

end of worries

[CrAsian]

+1 for cruise control unless you drive in areas with a lot of incline/declines.
if you're trying to drive to conserve gas and you hit an incline, the stupid cruise will hit the gas hard to get back to the speed you set it for. you'll see a nice spike in the rpms.

[*007*civic]

Originally Posted by CrAsian

+1 for cruise control unless you drive in areas with a lot of incline/declines.
if you're trying to drive to conserve gas and you hit an incline, the stupid cruise will hit the gas hard to get back to the speed you set it for. you'll see a nice spike in the rpms.

very true

[KingMarineM16a4]

Putting the car in neutral while decelerating will use more gas than keeping it in gear. The engine has to give enough gas to the engine to keep it running at idle; as opposed to the engine speed dropping it doesn't use any gas.