Armour combat values

[Issey1999]

In the rules book heavier armoured vehicles have larger Combat Values in the examples given at the end of the book. I can only assume this is to give a realistic value if a heavy tank cv5 and a light tank cv1 collide. But from what I can see this also gives bigger vehicles a better chance to hit when firing AT rounds as the CV is bigger. Am I correct in this?

If it is the case couldn't Armour rating be added instead of CV for collisions and lower CV's be used to reflect worse crews for firing purposes?

Thoughts please.