This is because internal combustion engines, such as those used in natural gas vehicles and in today's gas - powered automobile fleet, are incredibly inefficient. (earth-policy.org)
If you took the whole U.S. automobile fleet, which is more than 200 million cars, and converted one - third of the fleet from conventional lubricant to a synthetic, you could gain 2 percent fuel efficiency. (discovermagazine.com)
«There are at least half a dozen City agencies in the Downtown Brooklyn area, all of which have access to their own automobile fleet,» he wrote in a Feb. 1 letter addressed to the mayor. (dnainfo.com)