A few automatic transmission questions and ideas
 

Do the latest automatic transmissions have any mechanical linkage between shifter lever and the transmission?
I'm guessing they don't though.

I was thinking what if I intercept the signals from selector lever to TCU (transmission control unit), and let it go into Neutral automatically when I'm coasting and put it back to Drive as soon as I accelerate. Of course there are many other cases to consider but you get the idea.

I looked into intercepting or overriding TCU but that seemed too difficult with modern ATs but faking the driver input seemed to be easier.

great idae BUT.....

I want to control when I decide to go to neutral coast.

I wouldn't want to be in neutral coast and sunddenly need to accelerate.
THe 1-2 seconds of lag would be very dangerous.
I only neutral coast when there is no other drivers or things are clear.
There would be tooo many variables in the desicion proscess to have it go into neutral "just becuase".
(imho)
Ps I have been neutral coasting most of my life, but since 2000, I have driven over 500,000 miles in two cars: a 1997 Avalon 216,000 miles & a Q45 258,000 miles

I do not intend this hypothetical feature to be engaged full time.
I'd have an 'ECO' mode button to activate it which will be turned off when start the car.
Besides, I'd rather have my both hands on the steering wheel when I need to steer, also I find myself forget to engage gear when I had to accelerate while I was coasting.

Another thing I had in mind was putting it in neutral whil I'm pulling both shifter paddles on the steering wheel. that should be much easier to implement.

Anyways, the real question is, is this actually possible? In the mean time I'll be reading the factory service manual for my car.

I haven't looked at the shop manual for your car, but a lot of automatic transmissions use heavy cables to mechanically shift when you move the lever, the only part that is done with electronic solenoids is shifting from one speed to another, even the kick down is often a mechanical linkage, at least on older automatics.

I did some research.
My transmission's model # is A5SR1. It is used in Kia Sorento too.

This A5SR1 is based on JATCO(Nissan) RE5R05A transmission, and apparently they are mechanically nearly identical. Jatco RE5R05A was(still is?) used in 350Z, G35, and Titan truck.

i've never seen a transmission which did not have mechanical linkage between shifter and trans.

most are computer controlled for shift points though.

I checked the service manual. You guys are right.
There's shift linkage.