You know that the cost of getting this petrol back to Earth from even Mars, the cost of the nearest planet, would be prohibitively expensive, right? That's even ignoring the cost and insane difficulty of MINING it from here.
It would be awesome if, indeed, we could just drill some oil on Mars and ship it here. Whether or not that can really happen is another matter. Would be interesting, though, if this hypothesis led to a cheap, efficient way to convert carbon and other things into petrol.
I think the dangers of global warming are severely overinflated, but I do think that we do need to prevent pollution in general. However, I wouldn't drive a Prius in favor of a Ferrari or something, much like many of the members here - I'd advocate changes in bigger pollution-causers, like factories, first.