Not what the article makes it out to be, as he's not actually racing the WRC cars as we know them, but still very very impressive nonetheless, he still beat two Group A cars and 3 Group N, results here
http://www.rallymexico.com/rallyamerica/TC22America.pdf
1:40 slower than the top driver, but only :40 off Ken Block in his A8 Focus(that's in hours)
Quote from the codriver, who posted this comment on Digg
I sold my e30 for my LegacyTotal investment in the car was under $5K, including all of the safety gear. As was stated we ran the Mexican National rally run in conjunction with the WRC event. The oldest car, aside from ours, was a 2002 A8 Puegoet 206 WRC. All said and done, our total budget was less than the purchase price of the next cheapest car in the event.
