Actually, he was the production line model.
But somehow, second choice has such a negative connotation, especially when you leave out the whole concept of what made him the 'younger car'.
He is not some second banana to KARR, he was supposed to be the new and improved version. Calling KITT a second choice is like calling a Pentium 4 a fourth choice to a Pentium. You know just as well as I do that you would take the newer, more improved choice, and wouldn't call it a second choice.