last edited 2009/04/13 11:19 (*
Much of my argumentation of efficiency goes down to reduce the vehicle/body ratio, and only the human body, bicycles and a fully loaded truck are around 1 or below this ratio.
But aside this considerations, there is also another aspect often forgotten. The amount of energy to move a heavy vehicle (e.g. 1,500kg) is also the energy that vehicle has at a collision or crash - that energy needs to be distributed and transformed, and this is what a crash truly is, the energy which was used to move the vehicle needs to be released, mostly in deformation of the vehicle.
And here again, the vehicle/body ratio comes into place, when your vehicle is 9-12x times heavier than you, your body will be crushed and only 8-10% of the energy thereby released. What sounds a bit abstract, let me rephrase, the risk of physical harm done on the body is higher the heavier the vehicle you use. E.g. a pedestrian hit by a 1,500kg car is the worst case, the full energy of the car hits the body of the pedestrian, and deforms that body to release the energy.
Now, when you reduce the overall weight of the vehicles, you not just increase overall effciency since you require less energy to move the vehicle itself, but you also have less energy which in case of a collision or crash needs to be released - the lighter the vehicle the less energy is released in deformation of vehicles (cars or human bodies) - in a nutshell: lighter cars reduce the overall severity of crashes on humans and cars.
See my overview in Mobility of vehicle/body ratios.