My only mild concerns are lower than expected mileage (around 25). But the vast majority has been low-speed in town.
Don't feel bad.
My average MPG so far (1,800 mi) is 21.5.
My last car, a 2012 Ford Focus w/ dual clutch transmission averaged 22.7 over 5 years, 6-7 k a year.
Best was 37 mpg on the freeway, so it was no gas hog.
Driving while the engine warms up kills the mileage, not to mention sitting at red lights/stop signs half the time with the AC on.
Considering the difference in power between the two, I'm pretty happy the GTI is only 1.5 mpg less than the Focus.
Especially the way I've been driving it after 1k break in