Any time you hear the phrase "perpetual motion" or "free energy" you can assume you're being lied to. The laws of thermodynamics are unavoidable. It takes energy to move the mass of that car, it comes from compressed air, which took energy to compress, and you can't get out of the compressed air the energy it took to compress it, there'll always be some losses which have to be made up some other way. Eventually it's going to go back to the combustion of something, somewhere, even if it's solar-produced electricity. It will never be possible to run the vehicle on compressed air and use its momentum to drive a compressor to keep it refueled, it'll inevitably run down. The energy used to move the vehicle won't be available to recompress the air, it'll always use more compressed air than it can generate.