Toyota def needs to hurry up and put DI and a 6 speed in the 4runner. That will def help with the gas mpg and the hp and torque figures with the "easiest" fix. We're going into 2012 MY and it still has a 5 speed. What is up with that when cars like Chrysler are looking at 8 speed trannys?
As much as it would be nice to see a diesel in Toyota's line up, I also realize that it doesn't look like we will ever see one from Toyota. It seems that they're primarily focusing on hybrids for gas efficiency and considering how they're probably well ahead of the cafe requirements, they probably need to worry too much about getting their trucks to be too efficient.
A 6AT would offer minimal advantages in the 4Runner with the current engine.
At 70mph, in 5th gear, the current 4Runner engine is spinning at 2000RPM and making 31.2hp at the wheels (not counting drivetrain loss).
At 70mph, in 6th gear, the current GX460 engine is spinning at 1778RPM and making 34.4hp at the wheel (again, not counting drivetrain loss).
So, how do we increase fuel economy? We lower the engine RPM by making the cruise gear taller. So, we'll hypothetically put the GX 6AT in the 4Runner and drop the engine RPM to 1800. That gives you a 4.10 final drive to get the 70mph at 1800RPM in 6th gear. Your torque is 239lb-ft @ 1800RPM (compared to 247lb-ft @ 2000RPM of the 5AT). So, we run through the calculations.
At 70mph, in 6th gear, the 4Runner w/ the GX 6AT and a 4.10 final drive engine is spinning at 1800RPM and making only 26.3hp at the wheel (again, not counting drivetrain loss).
You're now making 15% less hp at your cruising speed so you'll be downshifting to 5th a whole lot more.
It really comes down to the 1GR just not making enough torque at low RPMs to really make use of a 6AT. Direct injection will really help that, though. The UR V8 in the GX makes loads of torque down low (~280lb-ft @ 1800RPM). If they offered a V8 4Runner, we'd see the 6AT. Personally, I think this is good engineering by Toyota. Yeah, they could throw an 8 speed transmission in the 4Runner, but it might just end up sandbagging the EPA rating and the owner is pissed that his transmission is shifting all the time and not getting near the EPA numbers. These 6, 7, and 8 speed ATs take a lot more parts to build that have more chances of failure. Shifting all the time, trying to find that perfect gear, also means that those clutch packs are engaging and disengaging that much more. More doesn't always mean better.
Interestingly enough, the Corolla, with an antique 4AT, gets better gas mileage than pretty much all the other compact cars (many carrying 6ATs) on the Consumer Reports fuel economy test loops, while on the EPA loop, all these other compacts are rated at 10% better. I think marketing pushes these 6, 7, and 8 speed transmissions even though the results don't seem to transfer over to the real world.
If anyone really wants to see my spreadsheets, feel free to PM me.
arty: :jaw drop: 
