Under inflated tyres –When tyres aren't inflated properly it's like driving with the parking brake on and this can cost a kilometer or two per litre.
Check your air filter--An air filter that is clogged with dirt, dust and bugs chokes off the air and creates a “rich” mixture – too much gas being burnt for the amount of air, which wastes gas and causes the engine to lose power. Replacing a clogged air filter can improve the mileage by as much as 10 percent.Don't be an aggressive driver –Aggressive driving can lower mileage by as much as 33 percent on the highway and 5 percent on city streets.Avoid excessive idling–Sitting idle gets zero kilometers per litre. Letting the vehicle warm up for one to two minutes is sufficient.