Someone in the comments explained what's really going on here (and it isn't cheating, though perhaps one might see it as a scandal): "The 6.67 factor is based

Someone in the comments explained what's really going on here (and it isn't cheating, though perhaps one might see it as a scandal): "The 6.67 factor is based on 1.00/0.15. The intention was an incentive for 15% of the fleet to be alternative fuel vehicles in the 1990's such as compressed natural gas (CNG), ethanol, etc. In this way if Ford had 15% of their fleet on CNG, then they would be equally weighted to their gasoline fleet in the fuel economy calculation by the EPA. The 15% incentive was supposed to be phased out as the actual percentage increased over time."