Article from the Navajo Times here via Pechanga.

Three reasons, it appears. One, the program isn’t designed for true “clunkers,” that is, the Buick up on blocks in the front yard:

“I have a lot of people come and tell me, ‘I’ve got a clunker sitting in the front yard,'” Becker said. “Well, no, the program doesn’t work that way. It’s designed to get clunkers off the road, not out of people’s yards.”

And two — Navajos like big vehicles:

Another problem is that the program requires buyers to trade for a vehicle that gets between two and four miles per gallon better gas mileage than their current vehicle, which generally means going for something smaller. It’s a concession most Navajos aren’t willing to make, said Marty Menapace, sales manager at Rico Auto Complex, because they use their vehicles to haul water, hay and other heavy cargo.

And three, bad rez roads means that there aren’t many clunkers that last long:

“”The folks that are really making out under Cash for Clunkers are folks who have vehicles from the 1980s,” Becker explained. “If you look around the reservation, there aren’t too many cars that age, for the simple reason that driving on the reservation eats up cars pretty fast.” For instance, one of Becker’s recent customers traded in a 2002 Dodge Ram. It had 250,000 miles on it.