ArvidG

I will do it in English so everyone can benefit:
This is not my discovery, I think I found it on a Golf Forum:
 
Locking/Unlocking a keyless-access equipped car while engine running using remote:
09 - Central Electronics
16 – Security Access (use 31347 code)
10 – Adaptation:
(1) Access control-Funk bei Klemme 15 ein      change to: "active" (factory state "inactive")
 
This will enable You to start Your car, leave the car with Your keys and lock the car with the keyfob from outside the car.
You need the keyfob to open it again!
If You stand beside the car With the keyfob in Your hand and try to open the door (by the handle) it will not work.
ArvidG