If you say so 
It is irrelevant. A jeep or any other vehicle should not be able to 'Go Inside' another vehicle/plane period. Now, if you could kill the driver from the outside with a well placed shot, that would be a totally different matter. Think of it this way...
If your tiger/panzer/panther/M4/T34 has it's (insert top machinegun name here) removed (or in the case of a T34, not have one at all) by attacking air units what defense do you have against this fast little jeep? You can't out run it, out turn it, or at this point, out gun it because a smart jeep won't let your turret turn on him. So basically you have a jeep now that can, without restriction, kill any perked/non perked GV in the game if it has even the slightest damage. There also is no defense from 'tossing a grenade in.' I can't lock my hatch to keep your grenade out. I can't shoot you in the shin with my sidearm or through the hatch when I realize you are leaving so I have no fear of a grenade.. I have nothing. I might as well be turreted with my engine out.
I thought this had been fixed, like many others have said.