I'm not getting the claimed fuel consumption

We purchased the reinvented Hyundai i30 in September and whilst I am very happy with the highway fuel economy of around 6.2 L/00 km, the around town is around 10.5 L/100 km and that is with very judicious use of the accelerator pedal.

I am not a lead foot and try to put as little input to get going as possible, but I notice that the instant fuel economy gauge goes to 30 L/100 km and stays there until around 40 km/h. After this speed, it seems to settle down a bit. I was wondering if you could shed some light on the potential causes of this problem.

I was hoping that after a few thousand K's it would settle down, but we are now at 7500 km with no sign of improvement. Your suggestions would be appreciated.