I finally bit the bullet the other day and bought myself VCDS to tinker with the cars. I was out checking my Superb for a few things and then decided to try something simple to break my VCDS virginity. I decided to enable footwell lighting in my Superb.
I get the guide from here and go through it all and methodically check every step. I enable the function; switch the car off, lock and back on to add the adaption. All fine, turn the ignition on and after 30 seconds I am bombarded with several error messages on the dash AFS not available, EML light etc. I poop my pants at this point thinking what had I done!
I tried to start the car and it just made a furious clicking noise and no engine start.....ohh no!
I admit my heart was in my mouth thinking I'd seriously cocked something up. I reconnected VCDS and did a scan; 13 errors inc controllers that couldn't be found and errors on others! 
I open one that is showing an error and look for the error message - battery level low 8.6v. Odd I think; I'd only been out in the car an hour earlier and it started first time on the nose.
I get out my DMM and measure the voltage and sure enough it's 8.6v. I disconnect it from the car and it rises to 11.4v with no load. Clearly not happy.
I go and check ECP and Halfords for battery prices as I need the car that afternoon. £60 odd quid for a Duracell 5yr battery will do nicely. I go back to the battery and measure again and it's risen to 12.2v! Bouyed by this I try one last time (with the DMM attached to monitor during cranking). It drops to 4.05v when cranking 
Definitely a dead battery then!
I get the new battery; fit, clear error codes and she's been happy ever since!
Certainly an interesting introduction to VCDS 