MPG .... 5-Speed vs 4-Speed

[theholycow]

Originally Posted by swng

http://drivingtv.canada.com/

At around 4:50 remaining is when they talk about the engine and transmission options. Here's the options:
1. 1.8l engine with 5 speed manual
2. 1.8l engine with 4 speed auto
3. 2.4l engine with 5 speed auto (maybe only available with AWD)

At 3:27 remaining they mention that they asked a Toyota engineer why the 4 speed automatic was used in the economy model. They were told that it's a new design that's lighter, more compact, and has different gearing (more optimized for economy) than the 5 speed.

I would add that it is probably still cheaper to manufacture, and people buying the smaller engine tend to want to pay less...and that people buying the bigger engine care less about FE and more about acceleration, so the 5 speed might be geared for that.

[swng]

Thank you theholycow! Incredible, you have really spent time to watch the video and provide the meticulous and enlightening response!

I appreciate that you treat it so seriously and I deeply admire your rational style of discussion .

I am happy to read the key words "they asked a Toyota engineer why the 4 speed automatic was used in the economy model. They were told that it's a new design that's lighter, more compact, and has different gearing (more optimized for economy) than the 5 speed." I have that 4-speed gear box on my Matrix. Though I still tend to agree with the ladies/gentlemen who say that more speeds can contribute positively to FE, now I appear to have personally found at least one exception, and happily it is found in the 2009 Matrix. Of course your posts seem to point out that other exceptions exist too (http://www.gassavers.org/showthread.php?t=10672). Is it not good news to gas savers who also want to spend less on their cars/transmissions?

Once again, thanks to you and the OP and the others for enhancing my gas saving experience!

[theholycow]

It's my observation that when they add more gears, it's rarely for the purpose of increasing fuel economy; it's purely for marketing to excitement seekers who think that they'll go faster with more speeds. Then later they make transmissions with that many speeds for fuel economy.

A 2008 VW's 6 speed transmission has the same 1st and 6th ratios as my 2008 VW's 5 speed's 1st and 5th. They just made the gear closer together...they're already way too close for fuel economy anyway.

I'm not sure that making them any closer even helps acceleration, at some point the time spent shifting outweighs the time saved by staying in a narrower portion of the powerband.

[imzjustplayin]

Originally Posted by theholycow

It's my observation that when they add more gears, it's rarely for the purpose of increasing fuel economy; it's purely for marketing to excitement seekers who think that they'll go faster with more speeds. Then later they make transmissions with that many speeds for fuel economy.

A 2008 VW's 6 speed transmission has the same 1st and 6th ratios as my 2008 VW's 5 speed's 1st and 5th. They just made the gear closer together...they're already way too close for fuel economy anyway.

I'm not sure that making them any closer even helps acceleration, at some point the time spent shifting outweighs the time saved by staying in a narrower portion of the powerband.

Yeah that's what I was thinking, making a CVT the better alternative. Though those gears supposedly give you a more "optimal" gear when you're cruising at a slow speed. As for it taking too long to accelerate because you're always shifting, well when you're at the higher speeds, you'll really need those gears in between in order to keep up your rate of acceleration because you could end up in an area where you're not in the power band right after shifting into the next gear, preventing you from accelerating further, but had you been in that power band at that specific MPH, then you'd be able to continue to accelerate. It's splitting hairs really and I just think having 6+ speeds in most cars is just for marketing and not really for anything else, but that's just me.

[civic94]

I also think theholycow is right on car companies making cars with more speeds for excitement purposes rather than fuel economy. my friends 5 speed prelude revs at 3,100 rpm at 60, and so is another friends 00 civic si. they have 5 gears but still revs high. I think the S2000 is about the same, with a 6 speed but the rpm's are up there (its rated at 26 mpg with a 2.0 liter inline 4 for the 2000 model year)

[spotaneagle]

Originally Posted by theholycow

It's my observation that when they add more gears, it's rarely for the purpose of increasing fuel economy; it's purely for marketing to excitement seekers who think that they'll go faster with more speeds. Then later they make transmissions with that many speeds for fuel economy.

A 2008 VW's 6 speed transmission has the same 1st and 6th ratios as my 2008 VW's 5 speed's 1st and 5th. They just made the gear closer together...they're already way too close for fuel economy anyway.

I'm not sure that making them any closer even helps acceleration, at some point the time spent shifting outweighs the time saved by staying in a narrower portion of the powerband.

its all about downshifting/ having more points to create certain amounts of power, i would think, if i were racing my car over a long haul i would probably go 1/2/4/ to save time on shifts, the torque at 3rd gear at 60 mph vs 4th gear at 60mph(where 2nd gear brings me to at top out) is about the same, so i would say that maybe a 1/3/4/5 or 1/2/4/5 shift pattern might work well to quicken it up on a 6 speed, tourque is made in equal amounts at 3k rpm as it is at about 4k rpm,
this maybe be different for a 1/4 mile run though as you would be shifting out of third while im already in fourth for example...
usually after 2400-2700+ it starts to rise at a steady rate from what I remember

i

it's kind of hard to gauge cause i dont go around redlining my car

[R.I.D.E.]

When I built my 76 280Z, I replaced the 4 speed with a 5 speed out of an 81 280 ZX. 5th gear was a .754 overdrive. The rear end was a 3.54. The car came stock with a direct drive 4th gear 4 speed.

That car would go 85 MPH at 3000 RPM in 5th gear.

I replaced the short block with a Nissan factory new short block, becasue they had a close out on them, when they started selling factory rebuilt engines. People were not buying the short blocks. It cost $375 and was brand new, not rebuilt.

It had flat top pistons that raised the compression ratio from 8.5 to 1 to right at 10 to one. Guage compression went from 160 to 190. It requuired some tweaking of the air flow meter and about 3 degrees less timing.

I was not hypermiling then, but even at 75 MPH on the Interstates I still managed to see as high as 28.5 MPG.

Depending on the engine size, my favorite configuration is gearing that gave me 30,60,90,120 in the first 4 gears. I foolishly replaced the 3.54 with a 3.90 later for greater acceleration.

The Echo revs at 2550 at 60 MPH. I wish it did that at 70 MPH.

One of the things I really liked about the VX was the tall gearing. It was almost the same as the 76 Z with the original differential.

I had a 59 Corvette that tached 2150 at 60 MPH. It would go 60 in first, 105 in second, 140 in third and god only know what in 4th. It averaged 21 MPG and that was before 1974.

regards
gary