Ok im sure we know the vehicles as of late have been weak. The problem here isnt the the vehicles, the problem is infact the damage output by the weapons.
In halo 3 I think any one can agree the vehicles were a little OP. You had the vehicles you controlled the world. Thats the big reason for the health degrade, but what If the weapon damage out put was different per weapon depending on the vehicle hit.
Ex
You hit a tank with a Br shot, it wont do anything, you hit a mongoose it will only do a little.
Instead of just having a set HP for a vehicle we would also make it so each weapon does varying damage to a vehicle
Anti vehicle weapons would do a good deal
Snipers, rockets, and what not
while normal weapons wouldn’t do anything but maybe a scratch