Remove the roof rack.This is another logical idea the more objects weighing heavily on top of your car, the more drag is created whilst travelling at high speeds.
Maintain momentum:-Constant slowing down and accelerating will increase the amount of fuel the car needs to work effectively, and so you will end up using far more.
Make sure your tire pressure is correct. less tire pressure makes gives rise to more friction. So fill air in your tire regularly.
Make sure you are driving in the right gear; slowest speed, highest gear
Reduce your use of the air conditioning.
Remove the roof rack.This is another logical idea the more objects weighing heavily on top of your car, the more drag is created whilst travelling at high speeds.
Maintain momentum:-Constant slowing down and accelerating will increase the amount of fuel the car needs to work effectively, and so you will end up using far more.