Coasting to a stop vs down shifting to a stop in manual transmissions

[UG_Passat]

I'm on a manual transmission enthusiast page on Facebook and holy hell this debate is heated. Basically many members believe if you coast to a stop in Neutral you should go buy an automatic and quit driving a stick immediately......they also say coasting causes more clutch wear. I could be wrong but isn't coasting easier on the clutch because your not slipping it each time you down shift? Many in the group say leaving it in neutral causes constant wear. I can personally drive either way but unless I am having fun I usually just coast to a red light ect. I understand the argument of less vehicle control ect but I was always taught it produces less clutch wear and synchro wear? How do you do it? Is one superior over the other. I personally think both have their place and executed correctly both can be viable options. But yeah what do you guys think?

Coasting means the clutch is still engaged against the flywheel, so no wear.

Shifting gears down causes more wear to the clutch material, as you said.

I've always coasted down to near wear 1000 rpms, then pop it into neutral and come to a complete stop. I did get rid of my 08 Passat with an ecu tune at 220,000 miles on the original clutch!!! My 02 Golf TDI, I replaced the clutch at 150,000 miles because I was making too much power and torque for the stock clutch. And I wasn't always easy on the clutch also, there was a lot of enthusiastic driving on weekends.

If I was coming up to a turn in local roads or a sharp turn in fun roads, then I would downshift to the appropriate gear and coast the rest of the way before making that turn. 2nd gear for the 90° turns, and the appropriate gear based on the recommended speed before the curve.

 

[UG_Passat]

You've never seen an unexpected falling tree or an avalanche shortly before an intersection? Sometimes you just have to get out of the way.

If you're in-tune with the car's engine and transmission on its behavior, then you can quickly downshift to the appropriate gear and get out of dodge.

 

[930.engineering]

You've never seen an unexpected falling tree or an avalanche shortly before an intersection? Sometimes you just have to get out of the way.

Thank you for convincing me it's a "serious" concern.

 

[y_p_w]

My Focus uses less gas coasting in N, than with engine braking, so I coast in N down hills or up to stops where I don't need any braking until the end. I'll rev match downshifts if I'm coming to a corner or down a very steep hill as it also feels dumb to burn up more brakes than I need to.

Any modern car will cut off fuel completely when engine braking. This was pretty well explained in this post:

Does putting automatic car in neutral for long idling periods relieve any engine/transmission stress?

So how does the engine run without fuel? FROM AN ARTICLE by Mike Allen: Here's the argument I get: "The engine is idling while coasting, so no less gas is used with the transmission engaged and the accelerator let up." When coasting in neutral, the engine is idling, consuming just as much...

bobistheoilguy.com

 

[supton]

I never needed any "power" in 34 years of driving.

I’ve not needed my seatbelt in 25 years, much less an airbag. But i’m not giving those up.

(not that i’ve ever had a fast car that could accelerate out of an issue.)

 

[jkasch]

If I’m in one of the overdrive gears (5th and 6th), I leave the clutch engaged until about 1,000 rpm. Then downshift into fourth until about 1,000 rpm (25 mph in my car). Push in clutch and put in neutral to a stop.

 

[y_p_w]

I’ve not needed my seatbelt in 25 years, much less an airbag. But i’m not giving those up.

(not that i’ve ever had a fast car that could accelerate out of an issue.)

Well - I've personally seen what happened to people who were in a vehicle where the airbag deployed and they were wearing seatbelts. They walked away from a pretty nasty little incident with only a few bruises. But yeah the seatbelt bruises were pretty obvious when someone was wearing sleeveless clothing.

Honestly - I cruise in whatever gear I'm in and then shift into neutral. I've tried downshifting and just never managed to do it without the engine just roaring. Even tried to blip the throttle but never got that either. I'd be interested in what automatic rev matching does though, but even then I'd probably just coast into the stop and shift into neutral.

It's just a habit. But at least it's not like my father. To this day he still rides the accelerator to hold up a hill rather than use his brakes.

 

[IndyIan]

Any modern car will cut off fuel completely when engine braking. This was pretty well explained in this post:

Does putting automatic car in neutral for long idling periods relieve any engine/transmission stress?

So how does the engine run without fuel? FROM AN ARTICLE by Mike Allen: Here's the argument I get: "The engine is idling while coasting, so no less gas is used with the transmission engaged and the accelerator let up." When coasting in neutral, the engine is idling, consuming just as much...

bobistheoilguy.com

Not my Focus, scan gauge always says more fuel is used while coasting in gear than while coasting in N. Plus you roll much easier/faster without engine braking. The Outback (SUV) says it cuts fuel completely and seems to act like it, but I haven't hooked up the scan gauge to see what's really going on. Also the SUV's/trucks have different emissions rules where I think they can let the cat cool down with engine braking, while cars cannot, so the Focus dumps fuel into the exhaust.

 

[930.engineering]

I’ve not needed my seatbelt in 25 years, much less an airbag. But i’m not giving those up.

While I do know in person some who survived accidents just because they were wearing seatbelts
I never heard of a single example of someone surviving because he stayed in gear and was able
to accelerate. It's just forum blahblah. Some particularly bored create issues where there isn't one.
.

 

[TiGeo]

While I do know in person some who survived accidents just because they were wearing seatbelts
I never heard of a single example of someone surviving because he stayed in gear and was able
to accelerate. It's just forum blahblah. Some particularly bored create issues where there isn't one.
.

Amen dude.

 

[Jetronic]

I’ve not needed my seatbelt in 25 years, much less an airbag. But i’m not giving those up.

(not that i’ve ever had a fast car that could accelerate out of an issue.)

They can accelerate into issues much better than out of them anyway.

 

[UG_Passat]

I never got that kind of "argument". What's so dangerous when coasting towards traffic lights?
I never needed any "power" in 34 years of driving. Obviously an American phenomenon, since I
never ever read about this on a European forum.

On a side note, the title says "manual transmissions". Automatic transmissions are another topic.

 

[Jetronic]

Not my Focus, scan gauge always says more fuel is used while coasting in gear than while coasting in N. Plus you roll much easier/faster without engine braking. The Outback (SUV) says it cuts fuel completely and seems to act like it, but I haven't hooked up the scan gauge to see what's really going on. Also the SUV's/trucks have different emissions rules where I think they can let the cat cool down with engine braking, while cars cannot, so the Focus dumps fuel into the exhaust.

Look if there's not a fuel cut switch active... The ecu is probably calculating what fuel to inject for the amount of air going in, but not actually injecting.

If there's fuel going in, there's power being made... Not a single car I've come across dumps fuel into the engine when coasting, except diesels when the dpf regen is happening or gasoline with gpf regen.

 

[SwampSurvivor]

Depends. I'll usually coast in gear (to take advantage of deceleration fuel cutoff) down to about 1100 RPM in whatever gear I was in before, then tap the gas and pop it to neutral with no clutch then come to a stop.

 

[Silver]

The wear not just on the clutch but drivetrain - gears, ujoints, suspension parts being jerked back and forth. No way. Don't drive your passenger car like a big rig.

 

[Avery4]

Unless I am expecting to have to accelerate again shortly, I slow down in whatever gear I'm in until I get down to almost idle and then I shift to neutral and coast. My logic is that this takes advantage of decel fuel cutoff for as long as possible without putting any additional wear on the clutch by downshifting through each gear every time I stop.

Not that there's anything wrong with that method either if done properly, I just don't feel that the tiny amount of fuel and brake wear saved from not idling for a few seconds is worth the effort of downshifting and the tiny amount of wear on the clutch. Keep in mind that clutch wear from shifting will basically be zero if you rev match properly, but rev matching the downshifts while slowing down negates the fuel economy benefit of staying in DFCO for a little longer.

 

[FZ1]

"A Man's gotta know his limitations."...........When to be in gear and when to coast. Basic driving 101.

 

[supton]

They can accelerate into issues much better than out of them anyway.

Indeed. All said, there have been times where I did feel underpowered merging onto a highway—I’d rather have power and not use it.

 

[vavavroom]

They can accelerate into issues much better than out of them anyway.

I have escaped getting rear-ended by accelerating and switching lanes countless times. We have lots of FOBies here and they drive like they did back home - all over the place.

 

[y_p_w]

Look if there's not a fuel cut switch active... The ecu is probably calculating what fuel to inject for the amount of air going in, but not actually injecting.

If there's fuel going in, there's power being made... Not a single car I've come across dumps fuel into the engine when coasting, except diesels when the dpf regen is happening or gasoline with gpf regen.

I believe engine braking creates a vacuum when the air intake is completely shut off. For idle there's usually an idle control valve. But the ECU can figure out that there's no accelerator and the revs are still reasonably high enough that the vehicle is coasting.