The compressed air electric hybrid solution, or EAV. The car that is driven by electricity, but gets its power from a compressed air generator. That sounds like an unnecessary conversion but the idea behind this is to regenerate as much energy as possible while driving (see drawing). It is more practical to have one unity to avoid expensive and complex power connections, like the KERS-system used in Formula 1.

The compressed air engine by Di Pietro's seems to be the most efficient solution. In this diagram the air engine and the generator are presented as separate components. This could of course be one machine, which has the rotor of the air engine and the generator on one axle. The air engine will run at a constant speed, because that is the most efficient. The small back-up battery (having 20 – 25% of the capacity of that of a full-electric car, and does not have to be Lithium-Ion) will fill in the “gaps”. This way the engine will be powered by the battery in city traffic, or in slow moving (rush hour) traffic. In these situations the battery is simply able to supply power much quicker than the air engine. It can be compared with an electric range extender like for example is used on the Opel Ampera.

The compressed air is stored at a pressure level of 4350 – 5075 psi, because more pressure means more fuel. This will be reduced to a lower operating pressure. More volume can be obtained from 1 liter of air through heating. This is what MDI does in there 3rd generation hybrid engine by using a small combustion chamber. This could possibly also be solved be using a type of glow plug like used in diesel technique, in an expansion chamber. The power for this glow plug is generated by a turbo generator. This is a turbo charger, which has a generator at the axle, instead of compressing air it generates electric power. When more power is generated than needed, it is stored in the battery.

The compressed air generator will also generate power for the battery while the car is driving on compressed air. Other components which could supply power are: the "brake generator" and solar cells, as already applied in the "B0" of Pininfarina. This way you will never have to charge batteries separately. When the car is stopped, or parked, the compressed air generator could go on running until the batteries are fully loaded. So “filling up” with compressed air is than all that it takes. The car can be made as “green” as one would like, depending on available financial means: better, or bigger batteries, using solar cells or not. Starting point will have to be: being able to buy an affordable basic model.