The latest generations of hybrids and small displacement engines with turbos fall well short of the fuel economy they’re supposed to deliver. So that begs the question, what technology does improve fuel efficiency? Researchers at the Department of Energy’s Pacific Northwest National Laboratory develop a new lightweight, space-saving CNG fuel tank. Mopar is considering building a version of the Ram pick-up based on the concept vehicles it showed off at Moab last week. All that and more, plus host John McElroy gives his insight on why commercial truck fleets in the U.S. are real interested in natural gas and propane.