this is not that what i want to see instead of my rotary just now
but very intresting
http://www.theaircar.com/howitworks.html
The Air Filter

The MDI engine works with both air taken from the atmosphere and air pre-compressed in tanks. Air is compressed by the on-board compressor or at service stations equipped with a high-pressure compressor.

Before compression, the air must be filtered to get rid of any impurities that could damage the engine. Carbon filters are used to eliminate dirt, dust, humidity and other particles which, unfortunately, are found in the air in our cities.

This represents a true revolution in automobiles - it is the first time that a car has produced minus pollution, i.e. it elimates and reduces existing pollution rather than emitting dirt and harmful gases. The exhaust pipe on the MDI cars produces clean air, which is cold on exit (between -15º and 0º) and is harmless to human life. With this system the air that comes out of the car is cleaner than the air that went in.

Now they just have to stick an electric motor to each wheel and we might have a performance vehicle which is clean for the environment. :)

You do not need to have electric motor you can drive it direct with the air pressure engine

video
http://www.motormdi.com/bbc.avi

They have been using compressed air engines on model aircraft for decades!

Hmm what exactly does the compressor run on?

Every time you exchange energy (chemical->heat etc) you loose some (not literaly , Einstein says you cant, but you dont get 100% conversion to the form you want).

So a compressor will use gas or electricity to compress air that drives the car. More loss than just using the gass/electricity to drive the car direct.

One good thing about this, same as all other alternatives (elec, momentum, hydrogen etc) is it can be produced more centrally, but that doesnt mean cheaper/cleaner tho.