Reduce The Total Weight Of Your Car
If you are currently keeping lots of different items in your car boot that you don't regularly need then it is worth taking them out. And if, from the last summer holiday, you still have the big Roof or Bike Rack on from the taking the kids away then remove it and keep it safe in the garage until you require it the next time round. On average approximately every 50kg extra weight will increase your petrol consumption by about 2%. There really is no need to use your car as a four-wheeled storage box, keeping your golf clubs etc in your garage, shed or loft instead of your car will save yourself a bit of cash.
Having external fixings on your car (such as a roof box) will also increase your vehicles aerodynamic drag because they change the way the air flows over and around your car. So to travel at the speed you normally would the engine has to work that bit harder which in turn is burning more fuel. So it is recommended you remove both internal and external items from your car because they are not only weighing you down but also affecting your vehicles aerodynamics!
Problems
May take a bit of time to take things out, then put them back in when you need them. But this should only be a tiny draw back for most people.
Related Resources
Book - How to Maintain Your Car and Keep It Running Smoothly
Image source: sxc / niloc 2005