Is the 8 speed automatic really the same as the ISF and the RCF from a mechanical stand point or if there a slight difference.

curious to hear from the gear heads how the 8 speed in the IS350 is built and geared compared to the ISF and RCF.

 

From what I've been able to gather, the 3rd Gen IS 8-Speed used in the 350 and 200t is the Aisin AA81E while the 2IS IS-F and RCF is an Aisin AA80E. From what I see, AA81E is a modified AA80e which has integrated g-sensors, apparently to hold gears in corners. I'm not sure what the torque capacity is or if the clutch pack materials are different between the two. The internet says the AA81e is different because of the sensors for g-force but I'm pretty sure the RCF has that too since it's a new feature? If so, why wouldn't it use an AA81E? Not sure about shift logic, management via software, etc. It does appear however all internal ratios in the all 8 gears of both transmissions are identical in both units. The 200t/350 appears to have a final drive ratio (diff) of 3.13 while the IS-F has a 2.97 and the RC-F 2.94.

Not complete information but some. If anyone can fill in the blanks for curiosity, that would be cool!

 

So which gives better MPG? using 8 speed auto or the regular Auto?

 

what are you even talking about?

your driving style will give you better mpg over and above anything else.