I agree that Pickens and the Senate and House Natural Gas Act sponsors focus on trucks... I have not heard anyone expect much from cng/lpg passenger car market in the US without widespread adoption by the OEMs. However, niche markets, such as taxi's and company fleets which can be served by a central gaseous fuel dispenser, are growing nicely, albeit from nearly a "zero' base ...
As you probably know, CLNE has a vested interest in the cng taxi market because of its recent acquisition of BAF (Oct 2009). This interest was detailed somewhat in the Q&A of CLNE's Q4 2009 Earnings (Mar 10, 2010), i.e.: