Chevrolet Optra Engine Poor Mileage

Sir Gud Day.. My Chevy Optra 1.6 At Only 6 To 7 Kilometers Per Liter. Somebody Told Me That Ecu Reflashing Can Help To My Fuel Comsumption...

Hello , I Have A Chevy 2005 1.6 Automatic Transmit Ion That Takes Alot Of Gas , I Checked It On The Computer And Everything Shows Its Normal...