When Ifrit doors are opened, one can fire projectiles through the vehicle and not damage it.
Grenades do not have this luxury. Instead, they bounce off an "invisible wall", with vehicle damage particle effects generating where the grenade hits said invisible wall.
Spawn as infantry man with AT, with IFRIT @ 100 meters away. Open IFRIT doors, hit targets through the IFRIT with the rifle. Observe dirt plumes from bullets. Fire AT, observe AT round detonate past IFRIT.
Toss a grenade and observe it bounce off the invisible wall. Damage particles may or may not generate.
Openable doors are being temporarily removed (until post-release).
Closing, since this is no longer relevant.