Speaking of rental car agency surprises, I booked a 4x4 through Dollar in Albuquerque this June for my attempt on NM-OK-KS-CO-NE, supposedly with unlimited miles. After some initial small talk at the counter, the rep disappeared into a back room and, about 15 minutes later, emerged to tell me that while yes, I could have unlimited miles, those unlimited miles would have to be driven within a 500 mile radius of Albuquerque. Nowhere did it state that on my reservation documents. Anyway, the Avis counter a few feet away "tried harder" and gave me a 4x4 Blazer on the spot for about $10 more. 1,899 miles, 2 hailstorms, many miles of unpaved roads (including Elbert's forest roads) later, and they probably wished they hadn't.