Need an advice or Comment Daihatsu Mira 2006

I have a Mira Car model 2006. Its engine has been changed once. I face problems with its fuel consumption. Without AC, it gives around 12 km/L in local run and with AC 8-9 km/L. I got it full tuning, change of spark plugs, cleaning of catalytic converter as advised by some, noticed no improvement. A mechanic says models as old 2006 have this fuel efficiency. Any one may comment!

• Style
  
• Comfort
  
• Performance
  
• Fuel Economy
  
• Value For Money