Hey all,

Just a little information:

1. The 5-speed auto tranny is brand new this year (as Edge has stated). It is on LX470, TLC, GX470, and 4Runner V8.

2. How does it affect fuel economy?? Well, the GX and 4runner has a relatively average (numerically low) rear axle ratio (3.7), which is good on fuel economy (vs. 4.10 on LX470/TLC). However, the downside is less torque multiplication (aka. less torque to driving wheels) than that seen in TLC/LX470, which is OK because the GX/4Runner is a lot lighter than LX/TLC.

Now, add in the 5-speed auto. The 5-speed auto has a very strong (numerically high) first gear ratio (3.5 vs. 2.8 for the 4-speed auto in V6 models), which should provide great torque in first gear...but, as above, does DECREASE fuel economy. So, the rear axle ratio fuel economy benefit is off-setted by the 5-speed's first gear ratio. So...if you do a lot of CITY driving (stopping at every stoplight & then accelerating), your fuel economy is gonna suffer.

However, the 5-speed auto 5-th gear ratio is around 0.7, which is decent/average (weak when compared to the 1st gear ratio)...thus, it is pretty good for fuel economy, but weak in torque. This is common to most automatic transmission with OVERDRIVE gear. You save fuel & less drivetrain vibration (smoother), but slamming on the gas pedal will produce little acceleration...thus, the transmission has to downshift to get more power for passing/climbing a hill. This means that if you travel on the highway a lot, your fuel economy is going to be good (remember, your rear axle ratio is numerically low at 3.7).

I know the above nomenclature is very confusing...but here is a simplification:

High/weak gear ratio = low numerically = good fuel economy = lower torque

Low/strong gear ratio = high numerically = bad fuel economy = high torque

For the 4runner, it is tuned so that it gets a good boost off the line/off-roading (strong/low 1st gear ratio and average axle ratio), BUT gets relatively good fuel economy on the highway (weak/high 5th gear ratio and average axle ratio).

As you can see, there is a tradeoff to torque and fuel economy.

BTW, the 4-speed auto on the V6 models has a weaker/higher 1st gear ratio (2.8 vs. 3.5 in 5-speed auto), but similar 5-th gear ratio as the 5-speed auto.

Hope this helps...and not confuse more people!