R 320 16 liters of normal consumption?

Hi guys, I drive a R 320 long and I’m actually very satisfied.Only the consumption bothers me.In the city he takes 16 liters.On track around the 10-11 liters.When I bought the car he didn’t take so much. Route 8-9 liters, town 12 liters.With time it became more and more.Have at the moment 18 inches winter bikes on it.Does anyone have experience with it?Can you do what?Software?And the tank indicator is very inaccurate, shows more times less.Do you have that in your R classes too? kbar for answers.