You got to do some man-math here. You never loose money selling the "old classic". Even if you sell it for, say $2000 less than you bought it. Because if you had a new car, being average here, you would have a $550 payment, in 6 months that would be $3300, so you would have a real cost avoidance of $1300 to put towards the new "old classic" you want to buy. And dont get me started on the lower cost of insurance and all the additional savings you are bringing with the "old classic" being cheaper.....
If you sell it for a profit, then you add the $3300 of cost avoidance to that money so you can now buy more classics. Its man-math.
If you sell it for a profit, then you add the $3300 of cost avoidance to that money so you can now buy more classics. Its man-math.