It certainly makes it easier if all you can choose is a colour and the car appears 2 weeks later. I was looking at German Hyundai site (after reading some i30 owner comments) and in Germany they are far more options to pick and choose.
I’m probably getting into an area I don’t fully understand but I’m sure I heard Hyundai UK was independent unlike VW UK which is owned by VW Germany ( I think). So I think maybe that is why Hyundai just get a stock of fully loaded i30N in a selection of colours as that is more suitable arrangement for their finances and say VW has the choice to spec a car if the prebuilt ones aren’t what you want. Totally happy to be shot down if talking rubbish.
On fuel economy, if asked, I’d say my Golf R gets average 33mpg. I know the combined WLTP mpg is pretty much the same, so pending a test drive I’d be happy to look at WLTP combined in other cars and rate them accordingly. Think i30N is a combined 34mpg but as mentioned before fuel economy can go up as well as down.