servotronic
 

as i'm entirely unaware what the difference is, can anyone tell me what (if anything) gives away that the car has it? and for us uneducated urchins at the back, what difference it actually makes (not what difference its supposed to make) Ta muchly.

Cosmetically, no difference.... The build code is 1N3 for servotronic and 1N1 for normal steering, so checking the service book or spare wheel well will reveal the truth....

Feel wise, the servotronic steering is lighter at slow speeds and heavier (normal) at higher / motorway speeds....

Personally, I like it. For parking etc its really, really light and can be turned with no effort at all, it feels more luxury, but I think less sporty as you lose some feel.....

When I moved from the S8 with servo to the RS6 with non-servo it felt right, as a sports car like that needs 100% predicatable well weighted steering IMO.....

HTH.

My car (A8 D2 sport 2002) comes without servotronic. If in future my steering rack goes bad, how difficult is to do an upgrade to servotronic?

I think it should be more than just a new steering rack...

There is a servotronic relay / circuit in the passanger footwell.
Mine went bad so I took it out, personally I feel steering is much better without servotronic, I love the slightly heavier feel at slow speeds, feels more precise as IT says.

Changing the rack is the Job of Satan, period :-(