No, a lot of cars aren't worth much. My 67 Park Lane cost $900 in 2004 and today it is pretty much the same. Perfect interior, rides and drives beautifully and will be taking it on a 600 mile trip yet only about $1000 street price. Why, because no one wants them. Second, I am realistic about the car. You clearly are a big fan and a big fan of 71 Polaras. To say you are a little biased would be an understatement. That is fine but you can lose the overall perspective. Because it is old and because you love them does not make them worth a lot of money much as you would like. The market determines that and the market is a whole lot smaller for these cars and it is not expanding but contracting. The middle class market and the demographics that cares for these cars is shrinking. The cars have been flat in appreciation for years in grade 3 or less. These cars aren't like owning stock in Apple where one can expect the stock price to go up every year.
Look at it this way. Think of the ship I work on, the USS Hornet circa 1943, as a car. Most all docents and ship restoration volunteers are over 70 years old. They have either had a connection with the ship, or a sister ship, in one form or another. I am the exception, as a few others are in their 60's, but the real key is that there are no volunteers younger than 60 and nor docents under 60. Being retired in 1970 means no new connections were formed consequently no younger volunteers. I have talked to the head of volunteers about the problem which he knows is just around the corner with five docents leaving in the month because of age or illness. One day the ship will be hard pressed for any kind of qualified volunteer like many other WWII ship museums. No one alive will have any personal connection to them except a few Naval nuts like me. So to will our cars be in the same boat. It's inevitable.