TL;DR - I continue to get better gas mileage with the new 5th gear. Still collecting data.
Every tank lasts longer than it used to. Barely.
This is a very short update, mostly because I assume that folks will be curious to know how the fuel economy is working out with the new 5th gear from an R452 transmission.
Everything I wrote in my First Impressions (see "In This Series" below) continues to be true. There, I also posted my initial MPG numbers for the first 1,500 miles of highway travel. I've completed another 3,600 miles, and wanted to provide another update.
| 5th Gear | Year | Miles | MPG | Average MPG |
|---|---|---|---|---|
| R150F | 2018 | 10,787 | 17.34 | 17.48 |
| 2019 | 20,383 | 16.96 | ||
| 2020 | 17,695 | 17.50 | ||
| 2021 | 29,529 | 17.80 | ||
| 2022 | 24,403 | 17.61 | ||
| 2023 | 10,662 | 17.35 | ||
| 2024 | 8,061 | 17.64 | ||
| R452 | 2024 (first update) |
1,466 | 18.24 | 17.86 |
| R452 | 2024 (remainder) |
374 | 16.54 | |
| R452 | 2025 (through May 3) |
3,285 | 18.15 | 18.15 |
That puts the R452 5th gear at a total of 5,092 miles with an average 18.05 MPG. Still better than pre-R452 - especially taking into account the heavier and wider wheel-tire combo - but less of a gain than the first few spectacular tanks immediately after the swap in 2024.
I will say - I was thrilled to see a 357-mile tank on the drive home from Utah that averaged 21.164 MPG! Had a nice tailwind there, between Salina, UT and Twin Falls, ID.
Look for another update one year from now.
In this Series
Breaking the 20 mpg barrier takes a feather-like foot. I've done it just a handful of times in my '98 4Runner. Personal best for a tank is 28 mpg heading south (downhill) out of the Owens Valley. City tires and a 50 mph tailwind certainly helped, lol.
Yeah, I've had only a handful of tanks over 20 MPG; understandable given that such amazingly high numbers were never part of the Tacoma promise, even when brand new and all stock, lol.
Fully loaded for a trip and built out as it is, I'm continuing to see numbers in the 18s and 19s, which is amazing. Still not "worth it" monetarily given what the new gears cost, but fun from an "I'm competitive with myself and always trying to get see if I can beat my average" perspective.
What speeds are you averaging on the highway? On my last trip from BC to Moab averaging 65-68 mph I saw about 17.5 mpg, 4.88 gears on 255/85R16 BFG MTs, 5VZ-FE in my 2003. And pretty loaded down. Although not bad I'm not a huge fan of the 2900ish RPM it runs to return that, considering a swap of my 5th but on the fence. Wish there was a 6 speed swap option! Great info, thanks for the summary
I generally run between 62-64mph on the highway.
Every truck is different of course, and at those speeds wind resistance is the biggest factor; a slight tailwind or headwind can affect things by quite a bit. And aftermarket bumpers, RTTs, etc. surely don't help.
MPG is also something that's difficult to measure accurately. We can't just read the number of miles from the odometer and divide by the number of gallons, since we need to adjust for non-stock tire size and gear ratios.
Anyway, as you can see, 17.5 was right around where I was with the stock 5th gear, and I'm far and away the most featherfoot driver I know. If you were actually achieving that on a similarly modded truck, kudos! Do you have a spreadsheet or app to track it? Always interested to hear how others do it.
Since this May (this update) I've got another 8,200 highway miles on the new 5th, and my average is creeping up. I'm at 18.73 mpg (again, highway) over those miles. That's pretty good - 7.15% improvement. And it's really nice (quieter) to have the revs lower on the highway.
Of course, if you think the stock 5th is gutless already and hate it, then the R452 5th is like putting on a wet sock. It's way gutlesser.
Yes that is true, although I have installed the somewhat corrected speedo gear I'm likely a bit off. Good deal of tail winds though most of the way there and back and she is definitely not interested in doing 80 through Idaho and Utah any longer!
Ahh yeah, I've got that 33-tooth speedo gear as well. And of course, we have to wrestle with about RPMs that are ~500rpm higher than similar speeds with an auto.
With the 33s, speedo gear, and 4.88s, my odometer is still off by a little more than 2%. Not bad, but something I need to take into account when calculating MPG, since it's a significant amount compared to the 7% improvement I've seen.
Nice looking truck! Always puts a smile on my face when folks like you are using them like they should be! 👍