SvdM, thanks for the interesting post. 6.24l/100km is pretty decent considering you mainly travel during peak hour traffic.
I've recently been keeping my Polo's tyres at 3 bar which is good for the open road but rattles around town.
I found that pulse-and-glide helps a lot, even when travelling at highway speeds. I accelerate to 110km/h then coast in neutral down to 90km/h, then accelerate again etc. I drove 400 km on Wednesday using this technique around 50% of the time and averaged a 5.8l/100km (with a fully loaded car).
I also covered the top grill with clear tape which has reduced drag slightly.
AndrzejM, I recently opened up my Polo's drum brakes and it seems like one of the shoes is rubbing slightly. I cleaned inside them as best I could (without stripping them down) but there still seems to be rubbing.
I looked for a shoe adjuster but they're automatic in the Polo 9n3 (mk4). Do you think replacing all the springs might help?
Here are two videos so you get an idea what I'm talking about.
Back right:
https://vimeo.com/134954731
Back left:
https://vimeo.com/134954730
Cheers