That's interesting, when I purchased my current Marathon, I asked the saleman this same question, because he had given me the Marathon weight values. I told him I assumed that this was empty weight.I asked Marathon how they weigh their coach and the salesman told me with tanks empty,diesel at minimum,no one in the coach including the driver.
He told me "no, that's full water, full fuel, and two passengers in the front of the coach".
I wonder which is true, or if practices have changed?
Ray