Less Mileage

I would like to share few things of this ALTO K10 (new Auto Gear Shift vehicle). I have experienced very less mileage - 12+ in city & 15+ on highways, I have concerted Maruti Suzuki technical team, they have said gradually, it will increase after 5000kms run, is it fine? any one experienced same with new cars ?

Best Features: Auto gear and power streering

Pros: Chilled A/C

Cons: Low space