When we were reminded to keep our speeds down while driving the 2015 Audi A3 TDI from Albuquerque to San Diego, it wasn't just the usual "be safe out there" rejoinder. No, it was sound advice, as this was no simple drive. We were challenged to cover the distance on just a single tank of fuel. That's an 834-mile route from the Hotel Parq Central in Albuquerque, all the way to the picturesque Hotel del Coronado, traversing multiple uphill grades, with altitudes ranging from more than 8,000 feet to below sea level on just one 13.2 gallon tank of diesel fuel.

How hard could it be? Well, the EPA says that the 2015 Audi A3 TDI gets 43 mpg on the highway; multiply that by the 13.2 gallon tank and you have a range of about 568 miles. That's impressive but 266 miles short of our goal; for that, we'd have to average nearly 64 mpg over mountains, the Continental Divide, and avoiding the kind of level, steady-state driving the EPA uses to get that highway number. We'd have to hypermile.

Hypermiling simply means beating the EPA's test numbers by maximizing momentum, and minimizing how much you use the throttle by coasting down hills, accelerating slowly from stops, and generally just going very slowly. It's common sense fuel management taken to an extreme, and would be mandatory if we were to go the distance. 

Sisyphean Task

I accepted the challenge on the first leg of the trip, a 104 mile journey that included a 3,000 foot elevation climb. We had to drive slowly if we were going to have any luck, and so for the 75 or so miles we spent on Interstate 40, I hogged the right lane, used the emergency flashers, and was generally the kind of Interstate nuisance associated with overloaded semis and senior-hauling RVs. 

Those same semis and RVs blew by us as we plodded along, but our sloth-like pace was maximizing the already-thrifty Audi A3 TDI's numbers, slowly creeping from the low-40s, to the mid-50 mpg range. At this rate, I thought, fuel economy would be in the 60 mpg range when we arrived at the Ice Cave and Bandera Volcano outside Grants, New Mexico. 

But the last 25 miles after departing the Interstate at Grants were uphill, with especially steep grade over the last few miles. Despite my lightest foot, our fuel economy plummeted from the solid mid-50s down to a disheartening 48.1 mpg when we finally stopped at the Ice Cave. A quick walk to the Cave itself lifted our spirits, but we realized that this was going to be as tougher than it looked. 

The ups and downs of hypermiling

After lunch, my driving partner Peter Braun took the helm, and it was clear that terrain was going to play a big role in how well we did as the mostly downhill route helped our economy tremendously. By the next driver's change at a rest stop on Interstate 40 a few miles north of Meteor Crater, we were solidly in the 50 mpg range again. Another long uphill run loomed, but after that was a gentle downhill slope all the way to our stop in Sedona, Arizona.

Sure enough, our economy slipped as I drove uphill, the desert giving way to Flagstaff's pine forests. But once we started coasting down the twisting, winding downhill road to Sedona it improved, and by the time we crawled past the breathtaking scenery and red cliffs to the aptly named Enchantment Resort, we were registering 57.1 mpg. 

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As good as that was, it wasn't good enough, and at dinner that night we were told that we'd be unlikely to make it. However, as consolation, Audi announced it was providing 2015 A3 Cabriolets should any drivers decide to bail out early. Suddenly, failure was an option.

The home stretch

Departing before sunrise with Peter at the wheel, we hit nearly every single red light on the way out of town. Yet his delicate throttle control ensured our economy stayed solid, and even though we gained altitude on our way to the first stop at The Ranch House in Yarnell, Arizona, his excellent driving had kept our economy in the 50-plus range. I took over the next leg, a mostly downhill stretch to our next stop in Blythe, California, gleefully watching our average solidify above 60 mpg for the first time. 

By the time we got to the lunch stop at Blythe we were still showing more than 60 mpg, but with temperatures in the 90s, and the next leg would be a hot, sweaty drive across the desert without fuel-wasting air conditioning. To stay cool, we put ice packs behind our backs, and let the air conditioning run for a few precious seconds as we coasted to a stop, when it wouldn't be using any diesel.

As our route took us past farmland, through desert wasteland, and past the Algodones Sand Dunes -- aka Tatooine -- the fuel computer's math relentlessly reminded us we didn't have the range to make San Diego. We agreed to stop at the sixth "bail out" point. With that new goal in sight -- and now with zero miles of range left -- Peter cranked up the air conditioning and whisked the last few miles away in cool comfort, rolling into the dirt parking lot of the Old Highway Café in Ocotillo, California, parking without even a sputter. We'd managed to drive an impressive 736 miles on a single tank of diesel fuel in a 2015 Audi A3 TDI, and we were happy with that, even if it was 100 miles short of the goal.

Hammer time

Once behind the wheel of the 2015 Audi A3 Cabriolet 1.8T, I mashed the gas pedal to the floor. Whisking along at legal speeds felt insanely fast after crawling for so long, and we simply drove, enjoying the scenery as we passed the remaining participants. In the end, two teams made it, a credit to the Audi's fuel economy...and the patience of the driving teams. 

But really, that was a foregone conclusion, right? I was curious what the A3 TDI would do in the real world, with a standard-issue lead-footed driver behind the wheel, so I had arranged to drive one back from San Diego to Orange County. Without even trying, the car's fuel computer registered an average of 46.4 mpg, not bad at all, and higher than the EPA highway estimate.

To me, that's more impressive. Sure, if you crawl along the whole way you can get good fuel economy, but few people are willing to put up with that kind of inconvenience. Instead, the real lesson is that A3 TDI will return excellent fuel economy even if you don't care about saving fuel. A 50 mpg average on the highway is possible, and wouldn't require a bigger sacrifice than simply going the speed limit, coasting down hills, and employing a few other minor tricks that you likely already know. 

The best news of all is that all this fuel saving is just icing on the cake for the 2015 Audi A3 TDI. The diesel responds swiftly to throttle inputs -- as big or small as you want -- and while the interior isn't as lavishly styled as other Audis, it's certainly comfortable enough for that long road trip you have planned.

Just save yourself some headaches and plan out a few refueling stops.

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