The new approach would see carmakers first put new models through laboratory-based testing, before submitting to a track test to determine a more accurate average fuel-use figure.
Variables such as wind speed, track temperature and weather conditions would be noted, with corrections made to the final figure, if need be, to ensure an even playing field for all carmakers.
The proposed method would present new challenges, with true aerodynamic advances and rolling resistance of tyres holding more significance on the road than in the controlled environment of current testing.
The EPA has previously voiced concern over current fuel testing methods, saying last year that variances between carmaker’s claims and real-world numbers were ‘unacceptably high’.
The Agency pointed to the cases of Hyundai and Kia in the US and Canada, who agreed to settle a class action brought by owners who believed the brands' claimed fuel economy figures were impossible to achieve.
Ford has also revised fuel figures recently for some of its hybrid models.
"The industry has some very good drivers, and we've noticed," EPA’s Christopher Grundler said last year. “It is not cheating, it is just taking full advantage of the rules.”
Ford and General Motors have expressed support for the proposed changes at this stage, while Hyundai spokesman Chris Hosford told Automotive News the Korean carmaker will reserve judgment until it sees the plans in full.
In Australia, current fuel economy testing involves a similar 'controlled environment' procedure to that of the US for all vehicles up to 3.5 tonnes gross.
A twenty-minute controlled test determines the average fuel consumption and carbon dioxide emissions of a vehicle, expressed in litres per 100 kilometres (l/100km) and grams per kilometre (g/km) respectively.
Phase One of the test involves simulated urban driving (city), while Phase Two tests the vehicle’s extra urban cycle (high speed).
The urban cycle averages 19km/h with the vehicle stationary for 30 percent of the testing time. The stationary period is a major driving force behind the emergence of stop/start technology, as a carmaker’s score is greatly improved if the engine isn’t running for 30 percent of the test.
The extra urban test has an average speed of 63km/h and a peak speed of 120km/h, designed to offer the best ‘real world’ reflection of a highway journey with varying speeds.
This data is then attached to new vehicles sitting in dealer lots on the ‘Fuel Consumption Label’, to ensure it is readily available to consumers shopping for new cars without the need for additional research.
While the market has historically seen buyers drawn primarily by size requirements or personal preference, fuel economy has become an increasingly powerful tool for carmakers since the turn of the century.
As new models are released, even incremental improvements in fuel consumption are viewed favourably, and carmakers are chasing frugality and weight-saving measures like never before.
MORE: Fuel news, EPA news