I've been diaappointed with mpg on my new GTI . average 26mpg so far over first 1500 miles , mixed driving usually fairly gentle with R foot but occasionally letting it rip. Also not revving too much for 1st 1000 miles to break in . Got 38mpg with Mark 4 2 litre petrol GTI when breaking in , fell to 28mpg afterwards. On paper 2 cars should give very similar mpg