“A runner when parked” is along the lines of “lady driven” or “never driven in the rain” or “mostly highway miles” since none of those statements can be proved!
Ask the seller what he would ask for it if it wasn’t a runner when parked or just discount the asking price by $500 yourself. That’s such a meaningless phrase. You’re buying the car as is which isn’t running now.
He doesn't want to put the effort into proving it runs so I thought I'd start at $1500 and go from there. He did state his wife doesn't know about the car and I do know where he lives LOL
