The Future Of The Manual Transmission

igozoomzoom

If I was to get new now, the new packaging puts the 3 hatch much higher on my list. I always liked it, but feel the 2.5l is overkill (and does not help MPG). The existing 2.0 was very economical, but I would not get a sedan.

In Canada, the 5-door with the 2.0L MZR engine has been available since mid-2008. It is designated as the GX model, while the GS and GT trim levels have the 2.5L MZR.

The 2011 Mazda3 GX Sport (the 5-door is called the Mazda3 Sport up north) comes with the 2.0L engine and 5-speed manual standard. Power windows/locks, keyless entry, ABS/TCS/DSC, 16” alloys and 4-speaker AM/FM CD system are also standard. It’s somewhat basic and the only options are 5-speed A/T and Air Conditioning, but it gets much better mileage than the 2.5L models.

Features such as steering-wheel-mounted audio controls, fog lights, cruise control, 6-speaker stereo and Bluetooth require a step-up to the 2.5L GS model. But the entry-level GX is still a great option to have...but only in Canada...

wwest

No manual transmission vehicle can make use of coastdown fuel cut.

With the fuel cut during coastdown some means would need to be provided to aleart the driver with a message..."it's time to downshift (again)" or fuel flow will be restore. Downshifting involves using the clutch...Oops, just stalled the engine. Or the driver happens to use the clutch with the fuel cut active and the engine will STALL.

ruking1

You are obviously not familar with passenger car diesels. It is actually understandable as 98% of the passenger car fleet are gassers. You might want to research this, as the (your) statement is not true, and not because I say it is not true.

elias

WW, perhaps I misunderstand you, but please know that approximately approximately 100% of modern manual transmission vehicles use coastdown fuel cutoff. Automatic transmission vehicles too... For the last 3 or 4 decades... And likely to be true for the Future of the Manual Transmission as well.
btw, the Future of the Manual Transmission is looking especially good given how much discussion it generates !
sincerely,
/e

wwest

I am not only "obviously not familier with passenger car diesels" I care not one iota to learn more than I come to know by pure happenstance. Other than pertaining to my JD455, that is.

So my statement pertained ONLY to gas engines.

Since you seemingly think the coastdown fuel technique can be taken advantage of with manual transmission passenger GASOLINE cars might you explain how...?

And while you're there please tell how manual transmission passenger cars with diesels engine take advantage of coastdown fuel cut.

Hmmm.... diesel passenger cars represent only 2% of the market...Does that mean only 20% of that 2% have manual transmssions, 99.6% overall...??

wwest

Well, it's pretty clear that one of us is misunderstanding. To my knowledge the coastdown fuel-cut technique I am discussing first came into use late in the last century. Wasn't much noticed until these new 6(10) speed automatic came into widespread use.

To clarify, the current technique COMPLETELY starves the engine of fuel, not even enough to sustain idle RPM. The technique will continuously downshift the transmission, but only enough to keep the engine turning over at some reasonable RPM. Once the roadspeed has declined far enough that engine RPM cannot be "safely" sustained then fuel flow is restored simultaneously with an upshift, often 2-stage/level upshift.

The transmission is then only shifted back down into first gear once the vehicle has come to a full stop, or nearly so.

volkov

Last year we spent 3 weeks in France doing the tourist thing and visiting friends who were living on the coast of the Mediteranian. We rented a Renault L'Espace diesel with a tiny 2.2L engine and 6 speed MT. The first nice surprise was that INSURANCE was over $200 cheaper for a stick than an Auto. My personal bias is that this accounted for most poorly trained N. American drivers who were more likely to get into trouble. A driver's license is not a right in Europe, it has to be earned. The second surprise was this little 2.2 coupled to a 6mt. This was a 7 passenger Mini-van that handled 6-7 passengers and all our luggage with no problem. The seemingly small engine had no trouble accelerating into traffic and purred at a barely audible level flying down the highways at 75-80mph. We saw over 30 mpg in mixed driving, and although the 6 sp was a bit busy in the city sometimes, I seriously doubt an auto could have posted the same results. Sure, I would have had been buried if street light racing with a V6 Sienna, but I could care less.
With 4 kids plus friends, I would buy one in a heart-beat but they don't exist here.
Why aren't vehicles like this available in NA?
1. Mindless sheep aka the average consumers have been sucked into a ridiculous marketing fabrication that any vehicle which doesn't do 0-60 in under 8.5 seconds is unsafe.
2. Consumers won't buy diesels or MT vehicles because they are unfamiliar.

qbrozen

wwest: yes, a manual transmission car also cuts off the injectors when coasting. My VW's OBC displays this the same way my 3 automatic cars with OBC have displayed it ... with the instantaneous mpg readout climbing to infinity. How does it work? Well, the same way as with an automatic. It doesn't allow the engine to drop below idle rpms. If you keep it in gear below that point, yes, it will stall. But rest assured, even in 6th gear, that doesn't happen till you are nearly crawling. If you step on the clutch, the injectors kick back in before dropping below idle rpms.

ruking1

I clearly said what I was referring to. So when you responded , it was apparent that you did not think it true for diesels, both automatics and manual transmissions. I gave (my) an example of a 5 speed manual. Indeed, I have a DSG and it is also true for the DSG (direct shift gearbox) . So the percentage of diesel manual /automatics is totally irrelevant to the issue (fuel cut off for both manuals and automatics and way off to the side DSG's, even as you state your swag as to the percentage of diesel manual transmissions.

wwest

Maybe I should have been saying fuel-starvation, not fuel-cut.

Yes, my '84 T-bird, V8/auto, slip it into neutral on the downside of the pass, and the MPG would quickly jump to 99 MPG, infinity insofar as the OBC computation was concerned.

Coasting along, coastdown, at ~60 MPG, clutch and the OBC will go to "infinity" although the engine is still being fed enough fuel for idle RPM.

Total fuel starvation during coatdown periods vs simple fuel "cut" to idle.

robr2

wwest: yes, a manual transmission car also cuts off the injectors when coasting. My VW's OBC displays this the same way my 3 automatic cars with OBC have displayed it ... with the instantaneous mpg readout climbing to infinity. How does it work? Well, the same way as with an automatic. It doesn't allow the engine to drop below idle rpms. If you keep it in gear below that point, yes, it will stall. But rest assured, even in 6th gear, that doesn't happen till you are nearly crawling. If you step on the clutch, the injectors kick back in before dropping below idle rpms.

I concur with this as well - my VW manual gasoline wagon does the same.

ruking1

Indeed one (I know you probably know this) can even hook up the VAG.com (software hardware diagnostic programs) to a laptop commuter to GRAPHICALLY demonstrate the "no fuel draw condition" on the coasting with ZERO throttle position. This is on gassers, diesels, automatic, manual and in VW's case DSG and or any combination.

There seems to be a subtle and not so subtle distinction between automatic/DSG and 5/6 speed manual transmissions, but I do not want to muddle the issues here until wwest has cleared up the issue in his own mind.

wwest

And just how often, might you think, that John Q Public uses engine coastdown, engine compression braking, in a manual transmission car....??

Even ME, driving my 996 C4 6 speed R/awd, I more often than otherwise simply push the clutch in during coastdown periods. Yes, there are times that I enjoy "sporty" driving, but those are rare in comparison.

And FULL fuel cut in a FWD or F/awd vehicle, fraught with peril.

Driver's, in general, being FE conscienous and thereby attentive to sequentially downshifting during coastdown ONLY to conserve fuel. Just doesn't happen..!

wwest

Even if what you say were true, which I don't believe for even a moment, we should keep in mind that with an automatic and an ECU in control the fuel-cut (FULL fuel cut) technique will be used EVERY TIME there is a coastdown period, independent of the WHIM(s) of the driver.

robr2

If I push in the clutch or simply coast while in gear, my OBC will show an instant mpg of infinity.

And FULL fuel cut in a FWD or F/awd vehicle, fraught with peril.

Fraught with peril?? Were you once a narrator for the Penelope Pitstop/Wacky Racers/Dudley Dooright cartoons??

xwesx

Is sequential downshifting not a common practice? I can't imagine doing it any other way! Always be in the correct gear for the speed; that's how I was taught to drive.

Maybe that is why brake pads on my vehicles always last 100K+ miles. I think others are insane to say 30-40K pad replacement is "normal."

colin_l

Brake pads and rotors are way cheaper than clutches.

plekto

Correct. The proper way to drive when you are slowing down or going downhill and then have to make a transition to a lower gear to continue on is clutch in, brake, and then properly match the engine speed to the gear that you need to be in. This requires a bit of skill, though, so many beginners never learn it. If you do it correctly, you almost don't even need to use the clutch to get it to drop into the right gear.

A good example of this is a typical freeway offramp where you are slowing from 70 to 25 mph to make a turn. Clutch in(move to neutral), brake, and then directly select 2nd when you get to ~25mph(exact speed varies and you have to blip the throttle a bit to get to the right RPMs for that speed, hence the "difficult" part for most beginners). 5th directly to 2nd, using essentially a slow-speed double-clutch technique You can also do the opposite as well when accelerating. I commonly just skip 4th entirely to save fuel.

Ie - unless you actually have a SMT gearbox and are forced to drive as such, you always get better clutch longevity and performance by selecting the gear that you need to be in directly.

qbrozen

Coasting along, coastdown, at ~60 MPG, clutch and the OBC will go to "infinity" although the engine is still being fed enough fuel for idle RPM.

This is incorrect. You should not be pushing in the clutch. As you indicate, the car would then need to feed enough fuel to keep the engine idling. If, however, you leave the vehicle in gear and lift off the gas, you will be using ZERO fuel, as the injectors are turned off completely by the ECU.

And, yes, I do this many times a day every day. When approaching each onramp, I try to time it so I lift early enough to coast to a safe speed to negotiate the ramp without ever touching the brakes. If I do it right, I'm able to go all the way around the ramp without touching the gas or brake. On one particular ramp on my way home, I'm coasting for about a half mile total using zero fuel and zero brake.

By the way, I hope you are shifting to neutral and releasing the clutch again. Coasting with the clutch pushed down will cause premature wear to the throwout bearing. Again, not that you SHOULD be coasting in neutral.

colin_l

The problem is that you decelerate rather rapidly due to engine braking. If you're trying to maximize economy, I am pretty certain that coasting in neutral with a manual transmission is the way to go.

For any type of automatic, don't shift of course. Just lift off the throttle.

xwesx

Interesting. I have never needed to replace a clutch. Seems like it would put more wear on other clutch components like the forks and throw-out bearing to keep the pedal depressed longer than necessary to shift.

My wife used to like to sit at lights with the clutch depressed the whole time (similar to the scenario presented by plekto). I finally was able to get her to break that habit.

xwesx

Depends on the engine RPMs based on the engaged gear. My old 69 Chevy tends to decelerate faster than any of my other cars because it is geared very low, but under 60 mph or so, it will slow quickly or slowly with "engine braking" depending my choice of gears. I rarely use the brakes on it. After 72,000 miles, I still haven't changed the front brake drum pads (yes, they're original!). Sadly, I did have to replace the rears about twelve years ago due to the seals in the rear axle blowing out and fouling them.

wwest

The mpg in that situation(***) is not really infinity, just beyond the computation capability or resolution of the OBC.

***Engine is bring fed enough fuel to sustain idle RPM.

wwest

I find that brake pads are much easier to replace, and far less costly (DIY for brakes) than a clutch disk, pressure plate, and having the flywheel turned.

"..always be in the correct gear for the speed..."

Absolutely, fully agree...except during coastdown..who cares.

Yes, all of us probably enjoy an occassional period of "stirring" the gears to attain a consistent level of engine compression braking for quickly slowing the car. But I don't think that "coastdown" is quite the correct term to be used for that.

If my front brake pads EVER last to 40K miles I would be pleasently surprised, 25-30K more common.

wwest

"..using zero fuel.."

How do you know, what is your foundation, for stating that your method results in zero fuel use..? I assume you either have authoritive documentation or have put an O-Scope on the fuel injector power and seen "0" duty cycle.

colin_l

LOL, oscilloscope? Let me make a copy of the results on my mimeograph!

You can see injector duty cycle with a OBDII scan tool. Or laptop plugged into your piggyback computer, if you have one. Oh, that's just me.

wwest

Yes, the automatic's controlling ECU always selects the gear ratio most appropreate at keeping the engine turning just "so", but the least possible compression braking.

Almost NEVER the proper gear for a quick return to acceleration which is where the 1-2 second "re-acceleration delay/hesitation most often bites us in the...behind.

wwest

I would have to see the scan tool display a KNOWN full fuel cut situation before I would trust it to indicate the same with a stick. Programmers often do not allow for the unknown or unexpected.

colin_l

?? One of us is confused.

The injector duty cycle seen by a scan tool is very real. It's the actual commands being given by the ECU at that moment. If it says 0, it's zero. I have never looked at mine when coasting either in gear or neutral. I can tell you duty cycle under full boost though.

ruking1

It is true with the automatic. It is still true, despite your disbelief and (your independent) lack of research. For some reason, you like the sound of one hand clapping. That is fine. The truth is your opinion does not affect in any way shape or form, the fact that it works in the (my) 5 speed manual transmission diesel. It is also true in my DSG. The same is also true with the 5/6 speed manual. Indeed, there are endless discussions (TDI websites) as to whether or not a car should be coasted in NEUTRAL or one of the many gears. For a host of reasons, it is better in one of the many gears.

At the 161,000 miles mark, the OEM front and rear brake pads and rotors have more than half left of pad material. I swag the F/R brake pads and rotors will last a min of 250,000 miles total (89,000 more miles MINIMUM) The clutch I have a reasonable expectation of 400,000 miles minimum. So really it is up to the driver/s to balance the wear on the wearable/consumable items or ... NOT. The same is true for higher mpg or...lack thereof.

qbrozen

How do you know, what is your foundation, for stating that your method results in zero fuel use..?

It is something I've read in many places from several tech experts. It is kind of an accepted fact these days on modern computer controlled cars. I'm surprised this is the first you've heard of it. I can't say for sure where or when, but I do remember reading it fairly recently in one of the major car mags I subscribe to (C&D, MT, R&T, Automobile).

I could hook up my laptop with my vag-com and confirm ... but since I don't need to convince myself, I really don't want to bother.

ruking1

Indeed I only mentioned it in the 5 speed manual diesel because the % differences and numbers are pretty dramatic (over the gassers and automatics and DSG's) .

nippononly

And just how often, might you think, that John Q Public uses engine coastdown, engine compression braking, in a manual transmission car....??

Well my name is Smith, not Public, but I use it all the time and achieve a running average of 41 mpg in around-town driving in my Echo which is EPA rated at 34/41 (before the idiotic 2008 down-ratings which left the Echo at 29/36).

I coast down to below 1000 rpm in whatever gear I'm in before clutching out, and the really nice thing about the Echo's engine is it's so sweet-natured that it allows this without any bucking or surging. Oh, and it has never stalled ever, don't know what that stuff was all about.....

....and at 154K miles I have also never replaced the clutch or the brake pads in this car, which may be partially attributable to this coastdown habit I have so ingrained.....but I do, as some have mentioned above, match the engine RPM to the speed of the car before engaging a lower gear, to reduce wear on the clutch.....

xwesx

Well, it's good to know that my brake pad life is not so terribly unusual after all!

plekto

My wife used to like to sit at lights with the clutch depressed the whole time (similar to the scenario presented by plekto). I finally was able to get her to break that habit.

My scenario (odd term, but whatever...) is that I basically double-clutch and throw it into neutral as often as possible and hold it in neutral through the deceleration until I get to the right speed for that gear. Then go directly to the appropriate gear since I can skip gears I don't want. If you do it correctly, you match the gearing and revs and the clutch basically takes zero wear when it engages. Driving old 60s cars without modern syncros led to this habit.(had to do this lest you ground gears all the time) I'm in neutral at lights almost 100% of the time if I can help it, as well, because my knees aren't getting any younger.

Of course, it also matters how the vehicle is set up. My Volvo 240 years ago would stall almost instantly if I let off of the gas in 1st while stopped. My 4Runner, well, I could take my foot off of the gas and idling in first, it wouldn't stall out. In fact, it would creep forward at 1-2mph like an automatic. Evidently, idle was high enough to allow for no gas situations and still keep running. I suspect that most modern cars are like this as well - they won't actually stall out from fuel starvation without you really trying to make it stall.

robr2

This is incorrect. You should not be pushing in the clutch. As you indicate, the car would then need to feed enough fuel to keep the engine idling. If, however, you leave the vehicle in gear and lift off the gas, you will be using ZERO fuel, as the injectors are turned off completely by the ECU.

Dumb question as I am not an engineer - wouldn't the fact that the wheels are turning and the transmission is coupled to the engine since the vehicle is in gear, keep the engine turning without fuel use?

nippononly

Not with the clutch on the floor, no. The clutch is what couples the transmission to the engine. So when you clutch out, the engine's computer is forced to feed it enough gas to idle.

stickguy

yes, clutch engaged the engine has to be turning when the wheels are going round and round. and why it does not need to use gas doing it.

this is the beauty of a fully mechanical system, instead of an AT with fluid couplings and built in slippage.

robr2

Not with the clutch on the floor, no. The clutch is what couples the transmission to the engine. So when you clutch out, the engine's computer is forced to feed it enough gas to idle.

That's what I meant - in gear, clutch engaged, coasting, wheels turning, the bus goes round and round....

I tried it on the way in this AM. Coasting off the highway only a long ramp, left car in 5th and coasted - OBC read infinity. When I stepped on the clutch, reading jumped to about 40 MPG.

qbrozen

Right. Which is what I stated.

BTW, on a side note, my GTI is the first OBC I've had that reads up to 199 mpg before getting the "---" reading for infinity. All others I've had maxed out at 99mpg.

dudleyr

My scanguage goes as high as 350 mpg. Probably higher, but that is the most I have seen. Downhill in neutral at about 80+ mph. It never does go to infinity though. 2007 Accord.

qbrozen

that's because you are in neutral. Try going downhill, in gear, foot off the gas.

wwest

The fact that it displays "infinity" ("---") likely has NOTHING to do with actual MPG. More likely a computation limit, hardware, software, or in the case of my '84 T-bird "99" was the display limit. In that case the more proper, informative display would have been "--", indicating "out of range".

scwmcan

You can have drums with traction control and stability control, it is on lots of cars that way.

steine13

Really great. I haven't been on this thread in ages, and 5 minutes later I'm all worked up over this coasting business.

I've wondered the same thing in my car; as I coast down -- not much in the way of hills here in mid-MI -- the indicatated mileage on my scangauge is not high at all... i forget what it goes up to, but it's double-digit, and not "99."

And this has led me to believe that the injectors are still feeding in gas to keep the engine "running" as it were, even though I'm in an engine-braking situation. Now I wonder whether that's true, or whether the program jsut defaults to some high number.

The car is an '07 Pontiac Vibe 5speed. Anyone know what really happens?

Cheers -Mathias

xwesx

Not to fear, Mathias, I have a definitive answer for you, and it is one on which we can all agree - no speculation required!

The car uses less fuel than when you're accelerating or holding speed.

There, now don't you feel better?! :P :shades:

ruking1

That would be about it.

You know , it is truly like "looking for a small needle in a BIG haystack", to find a particular oem/models per hour idle fuel consumption. I have yet to find what the actual consumption rate is on the "no fuel draw" condition, like wise.

Having said that, I know it is .2 gal consumed @ idle per hour on the 5 speed Jetta TDI because of Vag.com graphs and folks ( far more into it than I happened to be) conducting experiments to sharpen the swag in +/- mpg. So a discussion number on a TDI is - 10 mpg. What percentage of that in the "no fuel draw" condition is unknown. However it is easy to swag it is some percentage and number WAY less than that.

wwest

There is engine idle while parked which can grow, be computed, to an instant MPG of -99 MPG, that's "minus" 99 MPG. But in that case the most you are likely to see is "0", computation limit.

On the other hand an "idling" engine during coastdown, downhill enough to sustain say, 55 MPH, can grow to infinity, "99"/ "--"/"---" before you reach the foot of the hill.

My '84 T-bird, 60 mph+ (plus enough to get me a speeding ticket as I reached the bottom) coastdown on the downside of the pass only went to "infinity" (99 MPG) once I shifted into neutral.

DBW is a requirement for full fuel cut during coastdowns or an idle air sourse that can be COMPLETELY closed. QUICKLY CLOSED and just as QUICKLY opened.

There are just simply to many variables, IMPORTANT variables that remain only under drive control, for me to believe that anything other than fuel cut only to idle would be viable in manual/clutch transmission vehicle

ruking1

Well I am glad you again agree with me.

In response to one of your past posts', I used the example of the 110 miles downgrade/hill from 7300 ft to sea level on the (DBW) 5 speed TDI Jetta. It is good to see you intergrate that information.

oregonboy

Hahahahahahahahhahahahahahahahaha
Negative mile per gallon at idle! You are such a kidder.