(September 8, 2013) Audi of America invited a few dozen auto commentators from traditional media and from industry blogs to test the fuel-economy mettle of TDI last week. And clean diesel came through.

The exercise was just part of the TDI Efficiency Rally that Audi and Volkswagen Group of America held last week not only to allow influencers to evaluate the capabilities of Audi clean-diesel models but also to press politicians and policy-makers to create a level playing field for the technology with electrified vehicles that now alone enjoy “green” tax breaks and other benefits.

Audi plotted a course through the highways and byways of rural Virginia and Maryland and, over the course of several hours, invited reviewers to drive the three Audis to see what kind of mileage they could achieve.

It turned out that the reviewers overall experienced significantly higher fuel economy than the official, EPA-approved mileage ratings for the vehicles. Under-rating of official and marketed clean-diesel mileage marks by the federal agency is one of Volkswagen Group’s concerns.

Audi Q5 TDI returned the biggest mileage premium over its rating, achieving individual performances of about 32 mpg to about 40 mpg during the “rally” by journalists, compared with its EPA rating of 27 mpg combined for both city and highway driving.

In the Audi A6 TDI, individual drivers were able to notch actual fuel economy ranging from about 33 mpg combined to about 37 mpg combined in a vehicle that is EPA-rated at 29 mpg combined. And in the Audi A7 TDI, reviewers reached as high as 39 mpg combined in a model government-rated at 29 mpg combined.

Mike Millikin of GreenCarCongress.com was one participant who came away impressed by how his rides performed as well as by the tide of persuasive information provided by Audi of America over the course of the two-day event.

“Definitely one of the pleasures of cruising around the countryside in comfort and quiet,” wrote one of the participants, Mike Millikin of GreenCarCongress.com, “was glancing at the fuel indicator and seeing how much was left.”