I think liquid natural gas could make sense for larger vehicles—trains, ships, and trucking. You have to manage it, really, because one of the challenges when you go to liquid is that you have to cool it down to extreme cold temperatures. So in a car, if you can imagine, you drive to the airport, you fly away for a week, and the whole time the tank is warming up. It has a vent, and now you're venting fossil fuel, which is a really strong greenhouse gas, into the atmosphere, and it's not really the right thing to be doing.
On May 1st, 2012. See this statement in context.