Comparable Vehicle Point: The car that ran for 280k miles was obviously in different condition, and therefore, was not truly comparable.The fact that the OP has a comparable Honda vehicle with 280K is another point.
I have many time seen ads that tout volvo's "million mile car" reputation. They are not million mile guarantee.
Volvo Point: I have a feeling there is a disclaimer associated with any claim that begins with "it will probably run...." Also, touting a reputation is not the same as stating the condition of a particular vehicle.
Again, I do think the OP would likely win a lawsuit. However, for the reasons I posted, it wouldn't be unreasonable for a judge to rule against the OP.