M030
M030 HalfDork
7/2/12 6:32 p.m.

A good friend of mine has a 2005 Scion tC with a 5-speed manual. He complains that it's turning too many RPMs on the highway. He says, and I quote, "this thing is geared like a berkeleying Volkswagen and it's killing my gas mileage"

One of the guys in the shop says that 5th gear can be swapped for a taller (numerically lower) 5th gear from a Tercel.

Does anyone know if this is fact or fiction?

KATYB
KATYB HalfDork
7/2/12 7:14 p.m.

i believe there is a gear swap from a tercel or scion but cant remember... however it isnt killing his mpg as much as he thinks. went through this with protege people back in the day. 5gear swap on a protege with a bp yileded no change in mpg despite the rpm drop.

curtis73
curtis73 GRM+ Memberand SuperDork
7/2/12 7:20 p.m.

There is a fair chance that he'll lose MPG by dropping the RPMs. Those little buggers do NOT like to lug down. My wife's first car was a 4-speed Tercel. Then we got her a 5-speed Tercel. MPG was exactly the same. The 5th gear slowed the engine down a bit, but it made it lug down - requiring more throttle opening to maintain speed.

There are also ways to swap the 6-speed in, but its a minimal gain. You add a slightly taller 6th gear, but the final drive goes to 4.27 or 4.33 depending on the application.

My wife's xB gets 32-35 mpg while spinning over 4000 rpms in 5th. Its all in his head. Tell him to just get used to the buzzing. Lowering RPMs doesn't improve MPG. Proper RPMs maximize MPG. Toyota's little 4-bangers aren't like other imports... They peak torque much higher.

corytate
corytate Dork
7/2/12 7:31 p.m.

same deal with my kia, I turn over 3k at 65mph, yet I get a steady 33 mpg per tank. It seemed like a lost some mpg's when I was trying to hypermile and shift before 3k instead of right at it.
It's a sweet spot.

Vigo
Vigo SuperDork
7/2/12 11:41 p.m.

Honestly i think it's kinda funny that people with sub-2.0L engines are ok getting only 32-35.

/troll

tuna55
tuna55 UltraDork
7/3/12 5:59 a.m.
curtis73 wrote: Its all in his head. Tell him to just get used to the buzzing. Lowering RPMs doesn't improve MPG. *Proper* RPMs maximize MPG. Toyota's little 4-bangers aren't like other imports... They peak torque much higher.

I came here to say this, but ... uhh... He did it for me. There is more to life than parasitic friction.

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