• 38-mpg-rated 2014 A6 TDI achieves 43.6 mpg
  • 38-mpg-rated 2014 A7 TDI achieves 42.7 mpg
  • 31-mpg-rated 2014 Q5 TDI achieves 38.6 mpg

Dashing across the country in less than 48 hours is no small feat, but three new diesel-powered Audi models, driven by a group of eight automotive journalists, have conquered the challenge. Even more impressive than the quick times posted are the fuel economy figures the trio achieved. Each vehicle involved in the cross-country trek -- the 2014 Audi A6 TDI Quattro, 2014 Audi A7 TDI Quattro and 2014 Audi Q5 TDI -- beat its respective Environmental Protection Agency (EPA) economy rating by a significant margin.

The A6 TDI, rated at 38 miles per gallon highway, topped the three vehicles in fuel economy. It posted a final average of 43.6 mpg, 15 percent better than its EPA highway rating. Next was the A7 TDI. EPA rates it at 38 mpg hwy, too, but the big 5-door fastback did 12 percent better, posting a final average of 42.7 mpg. Finally, the Q5 TDI topped its EPA highway rating of 31 mpg by 24.5 percent. It averaged 38.6 mpg along the distance of more than 2,850 miles.

Wayne Gerdes, a fuel economy expert and owner of the efficient-driving website CleanMPG.com, was among the team of drivers. Gerdes coined the term "hypermiling" to describe a style of driving that prioritizes efficiency over speed and comfort. But to travel from Pacific Audi in Southern California to Manhattan Audi in New York City in less than 48 hours demands more typical highway speeds. Drivers averaged about 62 miles per hour and kept the vehicles' cabins comfortable with automatic climate control set from 68 to 71 degrees.

Typical highway speeds and comfortable cabin temperature settings were necessary to illustrate that the challenge was more than a publicity stunt. Calling the drive Truth in 48, Audi intended to show that luxury and fuel economy are not mutually exclusive.

Gerdes described the real-world conditions that drivers encountered along the way: "Think about the big picture," he said. "We drove what most would call the ultimate 2014 Audi AWD luxury sport sedans and a crossover [SUV] over three major mountain ranges, through multiple highway construction zones and through eight major cities. These are not sub-3,000-lb lightweight compact and subcompact vehicles with a single driver onboard. Each of the luxury automobiles carried four full-size adults, spares and gear [for total loaded vehicle weight] between 5,500 and 6,000 pounds."

While some makes and models are struggling to meet EPA-estimated fuel economy in real-world driving, these diesel-powered Audi TDI models topped it in the Truth in 48 challenge. Drivers that log lots of highway miles should consider diesel as a fuel-efficient alternative to gasoline or hybrid gas-electric power.

What it means to you: Good fuel economy is an important factor for most new-car buyers. Diesels like Audi's TDIs continue to offer an excellent balance of performance and efficiency.

author photo

Nick Palermo is an automotive writer and lifelong car nut. He follows new and late-model used vehicles for AutoTrader.com, writes about vintage cars for Hemmings Classic Wheels and blogs on all things automotive at LivingVroom. He lives in Atlanta with his wife and twins.

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