Could a vehicle self-power itself using biomethane extracted from the air ?

Of course. You’ve said bio so that must mean it’s good.

shut the fuckup, you cocksuckker.

Not really, no.

There isn't a high enough concentration in the air to fuel something that could actually carry a human in anything like real time.

There are much better ways to collect bio-methane and fill a tank than to extract it from ambient air.

Dirac answered this question twice.  Once as Jim 2 and once anonymously.  

And I agree with the other poster.  Dirac likely made the question.  This guy is so obvious.  Too funny.

You would have to extract the methane from the air, purify and compress it so you will be able to bring enough of it on the trip.  So yes you could do that.  The problem is that it would be very inefficient with current technology, if you want to go green, the best solution we currently have is batteries to store the electricity.

Speaking off, today my battery bank was fully charged at 1PM, I am going to need to buy myself some more cells and build a much bigger one and a hot tub, to dump the excess energy into. (my current battery cost about 100 dollars a kWh)

Only if you live in a Very polluted area, like Elizabeth, New Jersey. 

UPDATE: I DID NOT CREATE THIS QUESTION.

That's a thought, but you'd have to run a whole lot of air through some kind of extractor. The only way I know to do it would be fractional distillation of liquid air. (Lol, see update). No, I don't think it would work, unless you had a vehicle the size of a house, and even then you'd have to have an additional source of energy to extract the methane; I don't see how it would be self sustaining. update: Not that I am an expert on this. LOL. In fact, it looks like scientists are looking at using Zeolite to capture methane. But again, I really think this would have have to be done independent of any vehicle!