I understand that in a friendly fire game we should be very hesitant to make exceptions, as it detracts from the realism and predictability with the game. BUT, there is such a LOW CHANCE that a friendly C4/tank mine ACCIDENTALLY kills a friendly vehicle, and such a high chance that it's actually being done on purpose, that it makes sense to remove their ability to harm friendly vehicles. As it stands, it's almost entirely a griefing/harassment tool.
If my c4 couldn't kill my buddies harasser, why would I not strap it to his hood and ask him to ram the nearest tank?
Because sometimes you want to C4 that tank that purposely went out of it's way to run you over and laugh at you while you were trying to kill an enemy beacon or run to save a generator from overloading.