This is just a random idea I thought of that might be cool.
First I've heard a lot that most consider vehicles to be generally underpowered currently and contemplating how the firing type of a weapon doesn't matter unless it's Ordinance when on a Vehicle.
This gave me an idea, mostly made with Tanks in mind (but could be extended to other Vehicles if needed):
Thinking of how they're treated as Relentless but some of their weapons (depending on circumstances) are forced to Snap Fire.
My thought was, what if instead of being forced to Snap Fire under those circumstances the weapons (mounted, not fired by people from Transports) that would Snap Fire under the current rules instead
would be treated as having been fired after moving without Relentless/Slow and Purposeful?
Makes no real difference for Heavy or Ordinance weapons, but does boost up Assault/Rapid-Fire/Salvo mounted weapons.
In particular those much maligned Storm Bolters on some Imperial Tanks would be a lot more attractive with this rule, and I'm pretty sure the Land Raider Crusader would have a field day with this idea!
Then again, this could just be a bad idea too. Just thought I'd mention it.