MPG's --- A/T vs. MT

[dparm]

Originally Posted By: pbm
I'm happy to have gotten so many good responses to this thread.
What I'm getting is that an M/T is capable of getting the same, if not better, mpg's than an A/T (depending on the vehicle).
I'm getting the urge to pick up a Focus or Mazda 3 M/T as a commuter car. The only problem is the rest of the family doesn't drive stick...we'll see how it goes.
Thanks for the reply's.


I would not get an MT for commuting. You'll hate it within a few months, and you can bet that the clutch is going to get worn pretty fast. Nothing beats a good ole torque converter for stop-and-go driving. (even the good dual-clutch systems tend to be a bit jerky at low speed since they are still basically a MT underneath)

 

[KrisZ]

Originally Posted By: dparm
Originally Posted By: pbm
I'm happy to have gotten so many good responses to this thread.
What I'm getting is that an M/T is capable of getting the same, if not better, mpg's than an A/T (depending on the vehicle).
I'm getting the urge to pick up a Focus or Mazda 3 M/T as a commuter car. The only problem is the rest of the family doesn't drive stick...we'll see how it goes.
Thanks for the reply's.


I would not get an MT for commuting. You'll hate it within a few months, and you can bet that the clutch is going to get worn pretty fast. Nothing beats a good ole torque converter for stop-and-go driving. (even the good dual-clutch systems tend to be a bit jerky at low speed since they are still basically a MT underneath)


That's an overly generalized statement don't you think? Not all manual cars and clutch system are created equal and some are very easy to drive even in heavy stop and go, while others are a chore. Same thing goes for driver preference, some people don't mind it while some do.

I drive in some heavy stop and go at times, but my Focus is extremeley easy to drive. The clutch is fairly light, but still provides good feedback and the gearing is perfect for engine torque. In most situations I can just put it in second gear and feather the throttle.

 

[FZ1]

Originally Posted By: pbm
I'm happy to have gotten so many good responses to this thread.
What I'm getting is that an M/T is capable of getting the same, if not better, mpg's than an A/T (depending on the vehicle).
I'm getting the urge to pick up a Focus or Mazda 3 M/T as a commuter car. The only problem is the rest of the family doesn't drive stick...we'll see how it goes.
Thanks for the reply's.
Well,then,that ain't gonna work,is it?

 

[SteveSRT8]

I agree that an MT isn't a good commuter car unless it's a more open driving area, in stop and go it can get old real fast.

I love the idea of no one else being able to drive it! Get something Charp just for you.

And AT versus MT is all about the driver, not the trans.

 

[badtlc]

I have a fair amount of stop and go with my MTX since I commute. Doesn't bother me at all. I don't get why people complain about it.

 

[IndyIan]

I think normally, the AT's EPA mileage advantage is just from having a lower ratio top gear. If they made the MT with same gear ratios it would get better mileage, but often the MT has a much higher ratio top gear and so its worse than the AT.
Also I don't know what the mileage testing protocol is for a manual trans vs. an auto?
My Focus has a shift up light which would have you keep the motor under 2500 all the time which gives it a 37mpg hwy rating. The same car with the 4spd auto only gets 33mpg hwy with a roughly equal top gear ratio, but I assume it was an old design with only the 4th gear locking the TC.
I imagine now with DBW throttles and locking the TC in most gears, the ECU can run an automatic trans car much closer to the
ideal throttle openings at low rpms that give good mileage.

 

[lovcom]

In 2013, an AT that is controlled by a computer chip, and having 5, 6, 7 gears will almost always outdo a human, given the same exact car. You can tell the AT what is up ahead, what to anticipate with your right foot on the gas. Even AT's have some "manualness" to them.

 

[IndyIan]

Originally Posted By: lovcom
In 2013, an AT that is controlled by a computer chip, and having 5, 6, 7 gears will almost always outdo a human, given the same exact car. You can tell the AT what is up ahead, what to anticipate with your right foot on the gas. Even AT's have some "manualness" to them.

On the flip side, like others have said, the automatics can be programmed to do well on the EPA test but not come anywhere close that mileage in typical usage.
I don't know of any manual cars that have this issue?
For mild hypermiling, given the top gear ratios are close, a manual will always be better, with the exception of some of the CVT's.

 

[KrisZ]

Originally Posted By: lovcom
In 2013, an AT that is controlled by a computer chip, and having 5, 6, 7 gears will almost always outdo a human, given the same exact car. You can tell the AT what is up ahead, what to anticipate with your right foot on the gas. Even AT's have some "manualness" to them.


Then why is that in 2012 and 2013 some of the top fuel efficient models, in their respective model lineups, are manuals? Like Cruze Eco or Mazda CX-5.

 

[badtlc]

The MTX will always have less power losses than an ATX (a DCT or DSG is an MTX) and it will always weight considerably less. These will always make an MTX worth considering.

 

[Smokescreen]

What is typical usage?

I can drive steady state at 55mph (90 kph) on my commutes because I have a double divided hiway with very few other cars/trucks on it at any given time. On the highway I attain fuel economy much above EPA ratings as a lifetime running average. In the city, I can match EPA ratings quite easily as well...in all my vehicles even as old as they are. I run up to speed on hills and conserve momentum...but that is about the extent of my 'hypermiling' skills. So how do I continually meet and exceed EPA ratings in a 16 year old 5.7L suburban with over 220K miles on it? This is real world driving with imperfect weather and road conditions.

So does this mean that I do not use my vehicles in a typical manner or that everyone elses "typical" driving manner is just not leaning towards fuel economy ??

On the hiway, steady state the loss of an AT is the same as a MT once the TC is locked, otherwise what is the point.

I think people are too on or off on the gas pedal and it louses up the possibilities.

 

[badtlc]

Originally Posted By: Smokescreen


On the hiway, steady state the loss of an AT is the same as a MT once the TC is locked, otherwise what is the point.



No it isn't. There is more power loss in the ATX due to the increased rotational mass.

 

[IndyIan]

Also the traditional automatics have a hydraulic pump running all the time. It might use a hp or two which is sort of significant when a 55mph cruise needs 15-20hp to maintain speed.

 

[SteveSRT8]

Originally Posted By: IndyIan

Also I don't know what the mileage testing protocol is for a manual trans vs. an auto?

I imagine now with DBW throttles and locking the TC in most gears, the ECU can run an automatic trans car much closer to the
ideal throttle openings at low rpms that give good mileage.


Great point, the protocol is standardized, so the test has inherent bias. Frankly a good driver with a stick shift should easily outdo an AT but in the real world an AT can enjoy the advantages of cylinder deactivation etc. which are greatly facilitated with DBW, etc.

Both manuals and AT's have significant rotational mass, check out the new ultra small 9 speed from ZF for fwd, it may have less than a manual! They have the pumping losses so low they are nearly unmeasurable, this ain't 1990 no more...

 

[sciphi]

Some of it boils down to programming. For example, the AT in the Fit keeps the engine at or above 1500 RPM when for a steady-state cruise at 30 mph on a flat road 1200 RPM would be just fine. Same with the AT in a 1.4T Cruze. My manual Cruzes 1.4T is happy as a clam at 1100-1200 RPM with little load on it. The AT model will keep the engine at about 1800 RPM, where the turbo spools. That is a lot of gas wasted for instant responsiveness.

Somebody on one of the Cruze boards rented a twin to their car while on a trip, except the rental was AT. They got about 6 mpg less than what their car had done in similar driving. Others have commented that the MT Cruze is more efficient than the AT just because the AT is programmed for sportiness, not efficiency.

 

[kam327]

The reason the Cruze Eco gets such high economy is because its manual has an overall ratio spread of 7 compared to 5.8 for all other manual Cruzes. So it's not the manual per se, it's the fact that they changed the gear ratio just for that model. It was probably simply too difficult to change the auto's spread.

If manuals were so much more fuel efficient then all the other automakers would equip their Eco trims with manuals only. But they don't.

 

[KitaCam]

I'm getting 10% better MPG with Kitacam than with any car I've had over the past 44 years, all 4 bangers/all MTs...but all 10 got 20+ in town/30+ on the highway.

...and I don't drive my MT like an AT...

The Kitacam will pull away nicely from barely moving @ 1200RPM, but I rarely let the RPMs drop below 2000...

I could upshift @ 2k but rarely do so under 2500, and typically upshift @ 3k-4k, and always have.

On the highway @ 70mph Kitacam's RPMs in 5th are 2600; I'd bet on an AT it'd be lower.

Soooo, without "babying" it and driving it like a (AT) Camry, I get 24+ in town/34+ @ a consistent 72-77mph, a bit better than the OLD/original epa estimate which are higher than the "new" revised numbers...

I see that newer ATs do get a bit better MPG, but even if I wanted higher MPG numbers I wouldn't get an AT to get them.

 

[kam327]

Look at the Elantra, both the auto and manual are 6-speeds.

Look at the fuelly data; I averaged all 10 manuals listed there and then took 10 automatics and averaged the fuel economy for each. 32.6 for the auto and 33.1 for the manual. Mirrors the EPA numbers which are identical for both.

 

[kam327]

Here's the MPG curve for my Focus DCT (auto). Done with a Scangauge and careful 2-way testing on a flat country road.

 

[supton]

I know the mpg's in my truck is horrendous in city because of the torque convertor. While i like the fact it will "creep" while backing up it means I'm having to brake the engine while slowing down, in addition to braking the vehicle--darn thing will not coast to a stop. At all. It clearly is going to eat brakes prematurely. It also does not do fuel shutoff like my TDi--it must have some set of rules (engine temp, rpm, etc) instead of "is it above idle rpm?"