Another thing I want to mention in relation to the topic is the body of KITT. As much as I think it would be great to have KITT in his old Trans-Am body, the fact is that it wouldn't work in the same reason why having KITT in a high-end sports car won't work. What I'm about to share with you is actually a reasonable explanation on a topic I've had a few times over at Knight Rider Online. You see, one of the things that made KITT great was the fact that he was a common car packed with a super computer. Trans-Ams were common on the roads, the running gag of people confusing KITT as a normal car made sense. You see, if you have a common car out on the road and it's following you, you wouldn't think twice that it's actually following you. Think of this: the Ford Mustang is currently a common model car out on the road. You're likely to see a variety of Mustangs from the past decade. So, if one was following behind you're car, you wouldn't think twice about it being a car following behind you may be packed with a super computer driven by an artificial intelligence. The fact KITT was a Trans-Am helped in surveillance and patrolling, because he was a common car that was readily on the road. That's why keeping him in his classic Trans-Am style, or even put him in a high-end sports car, would draw attention to the car even more (the Trans-Am because there's not that many classic Trans-Ams on the road, and a high-end sports car typically have a rather "loud" appearance to the point that it attracts attention). So, putting KITT in a commonly available car like a Camero, a Mustang or even a Dodge Challenger, makes sense because there's tons of them on the road, thus adding to KITT's greatest strength: the fact that people can mistake him for a common car.
I hope that makes some sense for people.