My son is 6'6'' and the drivers seat doesn't seem to go far enough back for him...is it stuck or is there a way of extended it more so he doesn't have to drive with his knees against the steering wheel?

I'm 6'3" and fit OK... but I don't think the tC is really made for someone that tall. Depends on his weight too... if he has some meat on him it'll make it even worse.

Try moving the seat forward and then back again. And also try changing the adjustments on the left side to lower the seat down a little. Probably SOL though.

make sure the seat isnt "jacked up" so to say. is the seat all the way to the floor? if its jacked up it will move him closer to the wheel

I'm 6'2" and found that the tCs are probably one of the few smallish cars with adequate leg room. However, I don't think I would want to drive it for more that a few minutes if I were 6'6".

Short of moving the seat brackets back a few inches, I think you might want to have him trade it in for something more accomodating.