Your friend was lying about how large the interior was. No way in hell did it fit a 6'-4" tall man. I'm 6'-2", and I had to squeeze myself into my friends DMC-12 several times. My friend even more so, as he actually IS 6'-4" tall.
They were incredibly cramped. It's one of the reasons why Micheal J. Fox was chosen to play Marty McFly in Back to the Future. He is very SHORT, and therefore could get in and out very quickly.
Your friend was just making more excuses to justify his getting rid of the vehicle. Oh, he was probably right to do so, especially as he probably made money off it. But interior room wasn't one of them if he were on the short side. lol