Diesel vehicles can be far more fuel-efficient than gasoline cars, but Audi feels its TDI diesel models are being treated unfairly by Federal and state lawmakers.

Last week, the German carmaker held a “TDI Efficiency Rally” in Washington, D.C. to make its case--and to highlight the high fuel efficiency diesels can provide.

Audi and its corporate parent Volkswagen say diesels should receive the same regulatory perks as hybrids and electric cars.

In a press release, Joe Jacuzzi, chief communications officer for Audi of America, said the company wants the government to give diesel a “fair shot.”

2014 Audi A6 TDI

2014 Audi A6 TDI

Audi: Give diesels Federal tax credit

“Do they [diesel vehicles] get Federal or state tax breaks? No." said Anna Schneider, vice president of industry and government relations for VW Group of America.

"In fact, in six of the states, diesel fuel is penalized with additional state taxes."

Buyers of plug-in electric cars (and a few other types as well) enjoy tax incentives, such as the $7,500 Federal tax credit for electric vehicles.

Audi suggests some version of that credit should apply to diesel purchases too.

MORE: 2014 Audi A6 TDI review

Electric cars are also allowed to use carpool lanes in some states with only a single occupant, as are hybrids in a few locales.

But the lack of government incentives isn’t the only issue, Audi says.

Audi and Volkswagen believe the current EPA testing methodology is biased against diesels.

2014 Volkswagen Passat TDI

2014 Volkswagen Passat TDI

VW: Change formula to favor highway

When rating fuel economy, the EPA weighs city driving at 55 percent of the combined score, and highway driving at 45 percent. While hybrids excel in city driving, diesels tend to be more fuel efficient on the highway.

Consequently, the VW Group claims its vehicles’ real-world fuel economy is better than what the tests indicate.

Indeed, it's now largely accepted that under some conditions--including high proportions of travel at highway speeds--diesels often outperform their EPA fuel-efficiency ratings.

As part of the TDI Efficiency Rally, Audi let a group of “media influencers” loose in its new range of diesel models.

In the Q5 TDI, Audi says individual drivers achieved 32 and 40 mpg in mixed driving; the Q5 has an EPA combined rating of 27 mpg.

MORE: 2014 Audi Q5 TDI review

Audi claimed similar mileage heights in the A6 TDI, which managed 33 to 37 mpg and is EPA-rated at 29 mpg combined, and the A7 TDI, which Audi says got 39 mpg, 10 mpg more than its EPA combined rating.

2013 Audi Q7 TDI

2013 Audi Q7 TDI

CAFE rules favor pickups?

A third major issue puts the Volkswagen Group at odds with the 54.5 mpg CAFE standard that will apply to all new cars and trucks beginning in 2025.

VW (along with Mercedes-Benz) did not sign the CAFE agreement, claiming it gave leeway to full-size diesel pickups, but not cars.

More recently, the Volkswagen Group advocated giving carmakers credits for manufacturing clean diesels, similar to those they get for building zero-emission vehicles.

MORE: 2014 Audi A7 TDI review

EPA: Diesels don't 'significantly' cut CO2

However, the EPA said diesels don’t significantly reduce CO2 emissions in like-for-like vehicles, hence the lack of manufacturer incentives.

The agency’s focus on vehicles with some amount of electrification is deliberate: When a car runs on electricity, it’s not emitting anything--and that's the goal.

Diesel continues to be the VW Group’s green technology of choice. Volkswagen’s TDI models have racked up strong sales, and Audi is preparing to send dealerships an expanded fleet of diesels, including the aforementioned A6/A7, Q5, and an A8 TDI.

MORE: 2014 AUDI A8 TDI Review

Criticism of the 54.5 mpg CAFE standard hasn't only come from Audi and VW.

There is some concern that the new law will make cars more expensive, and that it could cut new-car sales.


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