Here are some methods i use to get 50% more fuel efficiency out of my 2 litre diesel toyota.It sounds impossible to get 50 whole more percent but the internal combustion engine and the way we deliver the power to the wheels is extremely inefficient process, but it is easily achievable.
Before i started driving more efficiently i used to get about 10miles to the litre and now i get about 15 to 16miles per litre.It sounds like nothing extra but do the maths.
previous fuel consumtion at 10m/l = 200miles per 20 litres
new fuel consumption at 15m/l = 300miles per 20litres
so i get another 100miles "from nothing"!
Only about 20% of all the energy in petrol or diesel is converted to motion, the rest is wasted in heat, vibration, noise, which i think is just not good enough and thats why i think that the internal combustion engine is an old technology in need of retirement or at least semi retirement and used in hybrids.
There are 5 steps to increasing fuel effiency:
Velocity or speed