IMO, I don't think that LNG is a viable option. CNG is the way to go, even for long haul.
The "inconvenience" is almost totally due to the scarcity of infrastructure. Once CNG "fillup stations" are as ubiquitous as current "gas stations", the inconvenience disappears. I'm well aware of the energy density issue, but if the sole inconvenience is that I have to fill up more often, I'll accept that.
I stand by my original assertions.....fleets will be first, and drive the installation of infrastructure, then passenger cars will switch. One datum pointing in this direction is that most fleet "fill up" points that are established also allow the general public (early CNG adopters) to use them.
Further, I think that the order of switchover will be large local fleets (UPS/FEDEX/and similar) first, then long-haul fleets with CNG added to truck stops, and then the general public. Pretty much inevitable given the supply/demand trends.
Several owners of long-haul operations disagree.
UPS turns to LNG, not CNG, for natural gas fueled long-haul trucks
http://knowledgeproblem.com/2011/02/25/ups-turns-to-lng-not-cng-for-natural-gas-fueled-long-haul-trucks/
LNG Vehicles Are In It For the Long Haul
http://members.questline.com/Article.aspx?articleID=20703&accountID=1863&nl=12731
Volvo Trucks First to Market LNG Powered Truck for Long-Haul Operations
http://www.theautochannel.com/news/2011/05/31/534869-volvo-trucks-first-to-market-gas-powered-truck-for-long.html
Trucks Run On Natural Gas In Pickens Clean Energy Drive: Freight
http://www.bloomberg.com/news/2012-02-29/trucks-run-on-natural-gas-in-pickens-clean-energy-drive.html
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Helping to build the infrastructure, Clean Energy Fuels (T. Boone Pickens) is building 150 stations across many of US highways.
Natural Gas Filling Stations: Few and Far Between
http://online.wsj.com/article/SB10001424052702304707604577422252404819664.html
In my opinion, we will see a build up of both CNG and LNG retail, often at the same highway truckstop location.
LNG will become a fuel of choice for long-haul, marine and locomotive. CNG will be used more by residential and light commercial.
Shell is investing in LNG for Marine transport.
Shell to make LNG available as marine fuel, starting in U.S. Gulf market
http://www.marinelog.com/index.php?option=com_content&view=article&id=1306:2011sep00072&catid=1:latest-news&Itemid=195
Wärtsilä and Shell sign co-operative agreement to promote use of LNG as a marine fuel
http://www.wartsila.com/en/press-releases/wartsila-and-shell-sign-co-operative-agreement-to-promote-use-of-lng-as-a-marine-fuel