I've looked at this screen briefly but have no idea what the design and behaviour of the magic blue wheel in the middle is supposed to represent. If anyone can enlighten me...

 

To my knowledge each segment is 15 seconds of driving and more blue in each segment the "better" you have driven. The middle wheel offers advice such as when you are being eco, or need to slow down. Other than that, it's a bit of a mystery to me too.

 

I currently have it on my 17 polo. I used it for the first few weeks and don’t bother anymore. As said by Tgolf the main circle is 15 seconds broken into a complete cycle and your average is based on this. The highest score I’ve ever managed was 85, driving at 50 on the M1 for what felt like hours and the best efficiency was 53mpg. You definately can’t get a perfect score in the polo so it’s reasonable to assume the same for the different model car.

the wedges to the sides of the main circle respond closely to the up and down gear recommendation; driving in 3rd doing 60 will lower your score, doing 50 in 5th will settle in the middle and so your wedges will be full.

it’s fine for a while

 

the wedges to the sides of the main circle respond closely to the up and down gear recommendation

I love how VW didn't bother to adapt this UI for a car with only one gear

 

I love how anybody bothers with it or takes any notice of it at all!

 

agreed. When I got the polo it was such a bonus to have a touch screen built in. you just have to play with the toys!