Coasting in neutral vs. downshifting

saturn
sl

#1

I own a 04 Saturn SL 4-door coup. It has a1.9L engine & 5 speed tranny. I coast, putting it in neutral, every chance I get when safe to do so. I never down shift to keep engine RPM’s (and fuel consumption) low. I figure the extra wear on the brakes is affordable and brakes are cheaper to repair than a new clutch plate. Am I right?


#2

I guess there can be many situations where shifting to neutral to coast can be a benefit but not always. And down shifting to slow the car is rarely a benefit while on long steep downhill grades using a lower gear to limit speed can be worthwhile and does no damage to the clutch or transmission. Years ago I saw a video of an old Rolls Royce driver training class that instructed shifting to neutral as soon as coasting down in speed reached the point where down shifting was needed and remaining in neutral until the point where it was necessary to shift to the appropriate gear ratio to continue on rather than shifting down from gear to gear as speed decreased. A glass of water was attached to the dashboard and a ‘good driver’ was supposed to never accelerate, brake or corner abruptly enough to cause the water to spill over the rim. Maybe driver training was a significant part of the Rolls Royce image of reliability and longevity.


#3

Back in the 1950s Saabs freewheeled down hills - basically idling while coasting. Probably a fuel-saving measure, although it meant brakes wore out faster. I think shifting into and out of neutral, or holding down the clutch, is OK for a driver who wants to, but not something I would bother with or recommend.


#4

Hey, that’s what I do! Do I get a free Rolls Royce?

Shift to neutral, don’t hold down the clutch: that’s bad for the clutch.


#5

Downshifting won’t burn more gas in modern electronic fuel-injected cars. In fact it doesn’t burn any gas at all. You’ll burn more gas coasting in idle. The engine computer knows by interrogating engine and transmission sensors that no gasoline is required, and turns the injectors off entirely. Try this experiment: At 35 mph in 4th gear, downshift to 3rd, foot off the pedal, and slow down gradually. You’ll likely notice a little surge ahead at about 5-10 mph. That’s the injectors kicking back on.

There is indeed some clutch wear w/downshifting, so you are right about that. Still I’ve double-clutch downshifted my Corolla every day for the past 27 years, and still sport the original clutch.

The biggest problem w/coasting in neutral imo is that you may encounter a traffic situation where you need to step on the gas quickly to avoid an accident. But that’s probably just quibbling, unlikely to occur. Good for you for adopting a driving style that saves gas and reduces air pollution :slight_smile:


#6

No real benefit to coasting in neutral, and a slight loss of control. In my 25 years of manual driving I kept it in gear. Coasting in gear doesn’t wear out the transmission or clutch.


#7

Yes, that’s what I’ve heard about coasting in neutral or pushing the clutch - you lose some degree of control. How significant is that? I don’t know. Most of my driving career is been with an automatic. Another scenario is that you push the accelerator forgetting that it’s not in gear, red-lining the engine. Again, I don’t know how long you’d have to have the engine at a high rpm before causing any damage.


#8

I doubt if the wear factor for or against amounts to much but it seems like unnecessary effort .


#9

When I learned to drive, it was against the l.aw in NY State to coast in neutral. I don’t know how that law was applied to cars like out 47 Fraser that free wheeled in overdrive,

There have been 2 major overhauls of our vehicle and traffic code since then so I have no Idea if that law still applies but I can tell you that as long as some truck drivers are getting paid by the mile, that law would be violated.


#10

Coasting is technically illegal in most states but since manuals are obsolete I don’t think the officers would know what you are doing.
I drive a 6 spd myself and coast all the time to reduce the wear on my clutch. The only danger is that if your engine dies, you would have no power brake and you are not in gear. Rare situation and having driven crappy cars in the past, I am very quick in starting the car by putting it back in gear.
I would not coast if you are gong down a long hill and have to use the brake but I assume that is a given.


#11

It was at one time against Federal Motor Safety Standards to switch off the engine while driving, that was changed many years ago to allow hybrid cars to operate. I would have to believe that “coasting” is also allowed.

I generally slow in fifth gear but shift to third gear to slow more quickly when approaching a traffic light.

Anybody riding in my car must pour out there drink if it has no lid before I start the engine, I am not interested in getting 100 years out of my clutch or tires.


#12

I’m pretty sure that keeping the water from spilling over the glass rim was in an effort to make the passengers comfortable @Nevada_545


#13

Aside from the distracting aspect of doing all this, you are wearing out your clutch at a fast rate. A typical clutch replacement is about $1500, so any gas saving gets wiped out. Additional wear on the brakes ads to further cost of ownership.

I would stop doing this practice.


#14

how does shifting into neutral when rolling to a stop cause cultch wear? you have to shift into neutral at the stop anyway.


#15

I do agree that downshifting without rev matching, with the engine repeatedly revving up, wears out the clutch. I’d just leave it in gear, then push in the clutch when I was going slow enough. Stop, put it in first. No time coasting in neutral.


#16

Another concern for those in hilly or mountainous areas is overheating the brakes on a long grade. Using a lower gear may be the only safe option in these areas.

I usually rev match RPMs as closely as I can. Give the car a little gas so that when you downshift, the RPMs don’t jump. That is putting wear on the clutch. If the speeds are the same or as close as possible, you will put a lot less wear on the clutch. I don’t bother to do this unless it is a pretty long hill, figuring that the extra wear and tear on the clutch to slow down to a stop sign or such isn’t worth it.

Some automatics these days use the gears to keep the speed down when cruise control is on as well. Of course there are a lot of things modern cars can do that the driver once did due to all the computers controlling everything these days.


#17

Every time you let out the clutch to reengage the drive train you are causing clutch wear. OP does this on downhill to presumably save gas or engine wear.

I learned to drive in the army and this practice was a big NO NO…


#18

one of the points NOT to coast in neutral after the acceleration is to let your engine and especially pistons to cool down to the normal operating temperature, keeping engine rotating at the higher PRM, while burning no or little gas facilitates this

in this sense, dropping to neutral right after acceleration presumably makes for higher engine thermal stress


#19

Why is that bad on the clutch? Clutch only gets worn when pedal is NOT all the way in or all the way out.


#20

I only know what I read at cartalk.com, and I’ve read a lot of comments that it wears out the throwout bearing. I like to keep my leg free.