practical implications of a reduction in effectiveness (Status value) of vehicles

[Embis]

Two questions on the effectiveness / status of vehicles:

Firstly,
I am Playing a scenario where I have a number of vehicles (lorries)  that are taking some long range fire fire. I noticed the effectiveness of these vehicles dropping to 25% as they receive fire.

I know that for non-amphibious Naval craft  effectiveness dropping to <50% results in sinking but are there any practical implications for loss of effectiveness for vehicles such as lorries? 

It would make sense to me that the cumulative effect of being under prolonged heavy MG fire at long range would eventually result in the effective destruction of an unarmoured vehicle but I don't see any practical consequence for having effectiveness at 25% in SB in this situation.

Secondly,
I also understand that infantry assaulting an armoured vehicle has the possibility of reducing the vehicles effectiveness dependent upon a number of factors. Might repeated assaults over time eventually result in the destruction of the vehicle as the effectiveness is reduced? 

I noticed that in Modern War Infantry assaults on Humvee's usually result in the Humvees destruction but repeated assaults on Bradleys  by infantry have not,  so my thinking is that there will be no cumulative effect resulting in destruction for repeated assaults.