Masters of the RAW, I present to you the following case: if you will flip through your handbooks to the USR section, you will find both the Jink and Ignore Cover USR. Note that the Ignore Cover USR relates only to potential WOUNDS, and says nothing of glances, penetrating hits or hull points. This seems to state quite clearly that Ignore Cover does not apply to hits against vehicles.
However, if you will turn to page 74-75, the third bullet under Vehicles and Cover, you will note that it states that a cover save is rolled exactly like a non-vehicle model would do against a wound.
RAI the USR is probably intended to deny all cover saves, regardless of target. But to muddy the waters even more the vanilla marine codex entry for the Thunderfire Cannon has a specific round type that has Ignore Cover...yet in the same codex, sternguard veterans have a specific round that ignore all cover saves. It does not have the USR but rather its own text, suggesting that their is a distinction between the two. Or perhaps this is just a writing error?
TL;DR What do you think, RAW lawyers? Is is cheese-mongery to allow vehicles to jink against Ignore Cover USR, or just a 6th edition change?