I've had really bad MPG from my car since I bought it. I've tried.....
...checked the tire pressures
...changed the spark plugs
...changed the coils
...cleaned the inlet valves
...replaced the thermostat
...serviced everything
....Etc etc.
I took the car for a careful drive through the countryside and managed 40mpg on that (very careful) run!
But day to day I can't manage any better than 20mpg
A lot of my driving is town based. But still. 20mpg sucks. I get an average of 320mls from a full tank.
I was expecting good things from the GTI but so far the car is no better than my previous 155 V6 or Subaru WRX....
Anywho.... I've decided to give up worrying about it