It might be due to the following:
Short journeys and uneven acceleration - accelerate evenly in short journeys
An electrical consumer is switched on – switch off all consumers that are not needed
Fault in engine management system - have the fault rectified from the authorized service center
Tyre pressure is too low - adjust the tyre pressure as recommended for the tyre size
Driving at high engine speed - select a high gear for fuel economy
Driving in hilly regions or driving with a heavy load - you tend to use more fuel in such situations