Been there, done that with the "friend" thing. I had a 1984 Kawasaki 1100 Spectre I bought new and had NO intention of ever selling. In 1997, I bought an used Harley and this "friend" started bugging me to sell him the Kawi because he missed having a motorcycle. I finally sold it to him at a "friend" price with the the strict stipulation, when he bought a Harley, like he really wanted, it ONLY came back to me and I would give him all his purchase price back. Yep, less than a year later, I found out he sold it for more than twice what he paid me. "Friends" like that aren't friends, and you have already experienced this with previous deals you've given him.
If you are afraid of pissing him off or losing him as a friend over this, don't be. Once he figures out he can't take advantage of you anymore, he will probably not keep in contact anyway.
You already have enough responses that the car is far more valuable than what he is offering, so take it from there. I have no doubt you could sell it on this forum quite quickly at a fair price AND have a new friend...