2000 Coachmen Santara 37RBS Diesel

[Buster52]

My wife and are looking at a 2000 Coachmen Santara 37RBS Diesel with 129k miles on it. We found it on Craigslist and thought first it was being sold by a private person but found out later the guy is a RV salesman. He says he gets 15 mpg on a trip from Fresno to LA and back, and at 55 over the Grapevine. That means twice over the Grapevine (I-5). So trusting the guy is problem. What problems should I look for? It has a Cummins 275, Allison 6 speed and 7kw Gen. I have looked at the price on Nada, but I have found it at times not to be correct, what price should I really pay of it? What fuel mileage should I really get?

Thanks

Buster

[EdT]

I have a 1999 Santara 351SB, no slide, with the same engine and transmission. My MPG average over 2 years has been 10.5 driving mostly 62 MPH. I paid WAY less 2 years ago with just over 70,000 miles. Not having a slide does make a big difference to some buyers. I really like my motorhome.