high consumption Fiat 500 1.2 2014

Moin Has been running the 1.2 500 for almost a year 70.000km My fuel consumption is extremely high Highway 7-8l According to Tacho City 9-11l according to Tacho I come with a tank filling around the 250-300km Far before the reserve lamp goes on Super E5 Total/Hem Ultimate and Vpower also tried out makes no difference Car I bought with 59,000Km A fresh maintenance made with timing belt, Wp,air filter, pollen, spark plugs,oil filter, brake fluid And all 10,000km a big maintenance spark plugs,air filter,pollen filter,oil filter spark plugs changed at 70.000km Ignition coil 63,000km changed Ignition cable 63,000km changed Lamdasonde Before Kat 63,000km changed I passed the AU What can it be for?