MPG .... 5-Speed vs 4-Speed
 

'Clyde The Ride' is an 06, first generation 2-wheel drive Tundra, with the 4.7 V8 and a 5-speed automatic.

While Clyde was in the shop: https://www.gassavers.org/showthread.php?t=11034

I rented my mechanics Tundra. Dex's truck is an 02, first generation, with the 4.7 V8 and a 4-speed automatic.

Both trucks are Access Cab.

The shift points on the 5-speed are about 500 RPM apart; keeping to a shift point of 2,000 RPM, I go through all gears by 40 MPH.

The 4-speed has shift points about 1,000 RPM apart and will be in 3rd until I let way off, to be in 4th at 40 MPH.

Blasting up an on-ramp at warp speed, both trucks will hit 5,000 RPM and achieve 70 MPH by the merge (I prefer slowing if necessary) but the 5-speed is probably quicker and has more 'go' left when I merge.

Both cruise at a tad over 2,000 RPM at 65 MPH.

Both trucks were used for courier work in the San Francisco Bay area.

This involved trips from Concord to Vaccaville to Berkeley and back to Vaccaville as a highway run; some commute driving, freeway (65 MPH) and surface street driving (30-45 MPH)

Gas Mileage. 5-speed.....................Gas Mileage. 4-speed.

6-02.. 382 mi.. 18.1 mpg****** 6-18.. 378 mi.. 17.8 mpg
6-03.. 247 mi.. 19.2 mpg****** 6-19.. 370 mi.. 19.0 mpg
6-04.. 213 mi.. 20.8 mpg****** 6-21.. 221 mi.. 18.3 mpg
6-07.. 396 mi.. 18.2 mpg****** 6-23.. 262 mi.. 17.9 mpg
6-09.. 242 mi.. 17.3 mpg****** 6-24.. 225 mi.. 18.1 mpg
6-28.. 403 mi.. 16.6 mpg****** 6-26.. 241 mi.. 18.1 mpg
************************** 6-25.. 290 mi.. 18.3 mpg

Total Average.. 18.4 mpg.***************** 18.2 mpg

I'm 95% sure that my dad's 2002 Tundra has the 5 speed, I remember it being a big deal to me back in 2002 when 5 speed automatics were rare. It might have been available only in the heavily-optioned models; his is the 4x4 with luxury and TRD packages.

Hmmmmmmmmmm.
Are you hinting that my truck might have the 5-speed because it is a TRD?

i think the reason the mpg numbers are similar is because its both cruising at the same rpm at 65 mph. i would bet the 5 speed gets better acceleration since the gears are more closer to each other.

This. If you look at fueleconomy.gov, sometimes you'll find the 4 speed manuals vs. 5-speed manuals get better mileage only because they're found on the "economy" models, not that there is anything inherently wrong with either one of them. If you have two vehicles with equally efficient transmissions, engines etc but one is a two speed and one is a 10 speed, assuming the top gears in both of these vehicles have the same gear ratio, try .710:1 (Overdrive) and you drive them on the highway, you'll get exactly the same mileage. The only real benefit to having more gears is better acceleration and from what I recall, better fuel economy in the city as you get the choose a gear that is "most optimal".

There are some exceptions to the lesser geared transmissions getter better economy b/c they're economy cars, one example being the '95 corolla with the 3 spd auto and 4 spd auto, the 4sp auto gets better mileage and that's probably because if they made the 3 speed have the same gear ratio in 3rd gear as the 4th gear in the 4 speed, you'd possibly have unacceptable rates of acceleration and or much worse city fuel economy. From reports of owners of the 3sp and 4sp, I've hear the 3sp runs higher RPMs on the highway compared to the 4sp and if that's true, that would explain the worse mileage.

I have a few of speculations:

1. All being equal, gear boxes with more ratios (gears) are likely to be heavier,
2. Gear boxes with more ratios are more prone to be selected and driven by
more "enthusiastic" drivers on the whole i.e. not without exceptions.
3. Cars with more gears are usually designed with performance rather than FE in mind, again not without exceptions though.

I think these factors may be remotely related to the findings, if such findings exist, that within reasonable limits, a gear box with more ratios may not necessarily return better FE than those with less ratios.

Because my Matrix only has four forward gears, I have for some time been feeling bad because I don't have one more gear, but somehow I think I have once read/heard in a review that an engineer of the car maker reportedly said that the 4-gear box could actually return better FE in the 09 Matrix (don't know if it is my model) then a 5-gear box. Regrettably I cannot remember the source and the details.
But ever since then, I feel happier.

Sorry that I don't have solid evidence to support what I say. I just enjoy joining in the discussion.

This is a great forum!

Well being 3200lbs and having AWD aren't things that are going to help fuel economy. As for the gears, just think of having more gears being like a CVT, it allows you to stay in the power band longer. Whether or not this will improve mileage, well that can all depend because some people like hypermilers will find a way to get good mileage as it is and the addition of those extra gears in between overdrive and 1st aren't too necessary with one example being that in a lot of cases, you can drive city speeds in 5th gear so if you're willing to sacrifice acceleration, you could go 1->3->5 or 2->4->-5 or 1->2->5.
If I had a manual in the Volvo I drive, when ever I encounter some slopes where I can gain speed w/o the accelerator, then I'd love to be able to just coast and shift into 4th/5th gear since I'm already at the speed where I can I fact drive in those gears but since I'm in a geartronic, the best gear I can start off with is 3rd gear.

Even a very small car with a small engine, which you might expect to need more gears to get better FE, does not.
https://www.gassavers.org/showthread.php?t=10672

Nice indepth discussion theholycow and the others!

BTW, I have found out the review in which I heard about a 4-speed gear box getting better FE. You have to go to DrivingTV.Canada.com (https://drivingtv.canada.com/) and search for the 2009 Toyota Matrix Test Drive Video. You have to click Search by Makes at the upper left corner of the page, and then find the 2009 Toyoto Matrix clip. The statement relevant to the subject discussed in this thread can be heard shortly after the middle of the video. Tedious, I know.
In case anyone really go there to watch the review, please correct me if you think I understand the video incorrectly.

Having more gears allows for more even spacing between gear ratios and less stress on the engine.
Pay close attention and you'll notice that either the lower, or the higher gears are 'clumped' together to give better performance in that driving range.