RE: '85 Jaguar XJ6 value?
I hate to break your heart, but it is not worth much. Your best strategy is to keep it, drive it, and let someone make you an offer. Ifound a buyer for a 1985 in fair condition for $500. last October, the car was not mine, I was helping a friend sell it.
The better condition it is in, the more money you will get, but even then, these cars are going through a "value revision" and at this point, they are at their lowest point. Hang on to it!
1984 Jaguar XJ-6 since 1989
1965 Jaguar S type since 2004