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
Step 1: Resistance
To reduce rolling resistance:
I always fill my tires to their maximum inflation pressure or maybe about 2 psi under,the higher the pressure the less surface area in contact with the road and therefore the less resistance therefore the less energy required to move the car along.The negative side to this is to fill the tyres with too much air,and the life of the tyre will be reduced because it will wear out in the middle of the tread so you need a good balance(usually about 2 psi under the max pressure printed on the tyre)This will probably increase overall efficiency by about 5-10 percent.
To reduce air resistance:
There isn't really much you can do to affect this one because as we all know the vehicle is a fixed shape and we cannot change it.But if say you have roof racks on the car,this can effect the resistance a surprising amount so take them off when not in use.Also a shark fin low profile type aerial is more efficient than a stalk aerial.Taking these off will increase overall efficiency by probably 5%.
Step 2: Momentum
Step 3: Acceleration
Step 4: Weight
Step 5: Driving Attitude
Step 6: Velocity
Did you know that if you double your speed, you quadruple your drag due to air resistance, yes, its exponential.so go slower.I travel at a maximum of 40 mph(or the lowest speed you can go in the highest gear you have)40mph might be a bit rediculous for some but even reducing your speed 10 or 20 mph can drastically save fuel.anything over 60mph basically just wastes fuel.