The Hoff tells TMZ ... his 'GOTG2' cameo only happened because director James Gunn was a huge fan of his '80s crime fighting show with the talking car. It's also how David ended up starring in a new discotastic music video with the other 'Guardians' stars.

Now David and James are working on a "Knight Rider" reboot ... with some changes, of course, to bring it up to date. There was already a remake in 2008, but Hoff told us why this one will be different.

And enjoy the music vid ... solid gold, man!