End to end automotive efficiency

Efficiency of cars measured often measured by fuel efficiency is misleading. Because it only considers the user end efficiency. Today an average petrol engine is about 35% percent efficient at its best point, but is only 20 percent efficient in urban driving. But many short trips with cold engine, amplified by cold weather and aggressive driving, significantly worsen fuel consumption, as do substantial time spent with the engine idling and losses in transmission. These real-world driving phenomena reduce the engine’s average efficiency so that only about 10 percent of chemical energy stored in the fuel tank actually drives the wheels. Hence out of the 100 units of chemical energy given to the car, only 10 units are available to drive the car.
Now an average sedan is about 1500 kgs, a driver and a passenger is about 150 kgs. This means that the car is about times heavier than the people it is transporting, hence 9 units of the 10 remaining units of energy were used to push the car and 1 unit was used to push the two people around. Hence the real world end to end efficiency of the automotive system is just 1%.
We truly need a revolution in power-trains and vehicle structure, if the automotive systems are to be made more viable.
Source: Scientific American 2007