The last two days of our Audi Mileage Marathon journey were uneventful jaunts through rural Texas, the northeast corner of New Mexico, and southern Colorado. The highlight of the weekend was Saturday evening's rodeo, held at an arena on the outskirts of Amarillo by local cowboys. Though clearly an acquired taste, there is something to be said for the visual appeal of bucking broncos and bull riding. The latter easily qualifies as an extreme sport since it takes a particularly fearless (or foolish) breed of man to get on 2000 pounds of enraged hamburger. Only one of nine cowboys managed to stay on the bull for the full eight seconds, another held on for six, but the rest didn't stand a chance. The bulls take no prisoners.

Our leg of the drive ended in Denver, where Audi announced the final mileage figures for our Chicago-to-Denver loop. The winning Q5 finished with a trip average of 37.3 mpg, the winning A4 with 42.6 mpg, and the winning Q7 with 29.6 mpg. Our own average fuel economy for the trip was a respectable 25.9 mpg. On Saturday, we managed to improve our fuel economy by almost half a gallon to 26.0 mpg from Thursday and Friday's 25.6, and on Sunday it increased further to 26.2 mpg. It's worth noting that, despite Audi's admonishments to the contrary, most of the participants used tricks in an effort to increase fuel economy.

The trickery gamut spanned a wide range, from the fairly mundane such as early gear shifting, smooth braking, and not crossing a certain rpm threshold, to turning the engine off at stoplights and drafting semis. Even with the more everyday style driving my partner for the trip, Jennifer Geiger of Consumer Guide, and I did, however, the TDI clearly offers a significant fuel-economy benefit over a comparable gasoline engine -- with plenty of grunt to go with it.

Impressive mileage aside, the million-dollar question remains the same: Will Americans go diesel with vehicles other than work trucks? Judging by the reactions we encountered on our 1800-mile cross-country jaunt, the mileage figures are appealing, but the higher cost of diesel makes people think twice. Regional success will likely come first, particularly in states like California and Colorado where the cost of gas is higher and the diesel price difference doesn't seem as extreme. But in states like Texas, a gallon of diesel costs roughly 70-80 cents more than a gallon of regular.

The best way Audi or any other automaker with diesel ambitions in the U.S. can combat public perceptions of diesels is to get regular folks into the cars, not just journalists as with the Mileage Marathon. Many people will simply refuse to believe a diesel can be as quiet and clean as a gasoline car until they experience it firsthand. Audi is no stranger to holding events like GM's now-defunct "Auto Show in Motion" or the Lexus Driving Academy. An "Audi Diesel Drive" event giving potential customers or current Audi owners the chance to drive diesel offerings could combat the pervasive negative view of diesels.

A positive indicator that Americans are willing to go diesel is the initial success of Volkswagen's Jetta TDI, which is already sold out for the rest of the year; Volkswagen plans to increase the TDI's availability for next year due to the high demand. It will take time to determine if that's a real trend or just a one-off spike. One thing is certain, especially in these trying economic times: It will be an uphill battle, but there is time before CAFE fully kicks in to get a significant portion of Americans onto the diesel bandwagon.