During my ten year ownership of a diesel Mondeo I regularly treated yhe car to a dose of diesel cleaner. This was on the advice of my service garage .

 

 Is there any reason to cease this practice with the Superb? 

I've taken up the practice of throwing a tank of super premium diesel in, every x tanks. I believe the only difference is the detergents added.

I exclusively used posh diesel on my Octavia. Imagine it's the same engine. On the odd occasion I put regular in I noticed the difference in both mileage and response.