Disclaimer: I really love driving, but I am not a I-know-everything-about-car-mechanics guy, so the following post is based simply on my empirical knowledge.
My first car (Ford Fiesta 1.25) is now about a year old and I must admit that I haven't always been treating it nice in terms of fuel consumption levels. As a result, it was gradually turning into a fuel monster, eating up about 7.9 liters per 100 km (or 29.7mpg). That was clearly over the limit, especially from an environmental point of view.
The change came after one of my tires (Hankook Optimo) went flat and more specifically when I decided to purchase a new set of tires (Bridgestone). Amazingly, the improvement was dramatic! Following the three key points below, I managed to reduce fuel consumption within a month from 7.9 liters per 100km (29.7mpg) to 6.9 liters per 100km (34mpg):
- New tires Switching from Hankook to Bridgestone, and having new fresh tires was a real improvement
- Changing gears in 3.5k rpm (4k tops) Not pushing car engine to its limits always helps
- Avoiding holes or bumps on the road (common phenomenon in Crete) & using gears to slow down car instead of hiting the break all the time
I hope that those tips might help, but in any case ask a car geek for this kind of task, I might be sharing some silly knowledge here!