Saving fuel is not rocket science, but requires discipline

If you want to save fuel when driving your car, then it typically comes down to some pretty simple guidelines:
1) Look ahead, minimize braking and acceleration manoeuvrings, try to "glide" as much as possible
2) Leverage the means your engine provides to minimize fuel consumption. This is different from engine to engine. It may mean to accelerate gently with one car, but to firmly accelerate and then glide again with another car
3) Adapt your speed to the topography you drive through. This may mean going slower up the hill than down the hill

If you follow these three rules and you know under what conditions your engine can optimally support you in doing so, then you can achieve astonishing results. Look at the foto (to the left). This is a BMW 330i Touring (model 2008) with 272 hp and almost 1'800 kg weight (with a family and some luggage). But you still can drive it using less than 6.5 liter per 100 km without slowing down the traffic behind you. The influence of the driver though is substantial. Doing the same distance with 50% more fuel consumption is easily possible and might also be more fun. But if the goal is to save fuel then fun has second priority. There's one exception. Rule 1) allows you to take curves very quickly to not have to break ;-)

One more comment: We often feel that cars today are not much more efficient than cars 20 or 30 years ago. Well, to have the performance of the described BMW 330i it took a Ferrari 308 GTB/GTS in the early 80ies and staying below 20 liters per 100 km wasn't easy with that car.