Is it possible to upgrade your regular key to a intelligent key on 04 TL?

 

Yes there are systems out there where you can add keyless access and push start and I have actually tried it before on a previous Tl of mine. Unfortunately the system did not work up to my standards and I ended up removing it. The range antennas for the keyfob did not work very good and the car would constantly lock and unlock as you walked around the car. It was super annoying.
Another example is one time I was loading and unloading stuff and moving things from the back seat to the trunk and the entire time the car was locking and unlocking due to position of the keyfob moving in relation to the sensor/antennas. I tried putting the antennas in several different spots and it did not help.
This was years ago so maybe they have better kits now, but the one I had I did not like.
What they need is similar to OEM setups where you place your hand in the door handle and it unlocks, not a antenna that will lock and unlock based on distance from the car. I also hated walking passed the car in the garage if I had the keyfob on me....you can guess what always happened lol.

Just search google for push button start and keyless access systems, you will see them. THe one I tried was made by "Advanced Keys"

http://www.advancedkeys.com/index.htm

 

Lol sounds pretty annoying. Thanks for the input. About to do some more research upon it.