G8 vibration

I have a 08 pontiac g8 gt. when i’m driving and settle in on a speed (any speed) i get a pronounced vibration that only leaves when i alter my speed even just the slightest. It feels like i’m driving a manual and am in the wrong gear where the rpms are too low. when i switch over to sport shift and drop it down a gear it always dissapears. My dealer suggests that i can drive exclusively this way. Not even funny. what do you think?

I think your dealer is an idiot. Well, you asked.

It sounds like the GM coil pack issues of old. I’ve never seen under the hood of a G-8, they’re too new for me, but if it has coil packs, that’s where I’d look first. See any arcing under the hood in the dark? Is the “check engine” light on?

Does your car have a ‘displacement on demand’ system? I think these were offered on the V8s. If it does, there could be an issue with the system. This would line up with when you encounter the problem and how you get it to go away. If that is your problem, the dealer service department is your best bet to correct it (I hate saying that).

Question # 1, is your car under warranty?

If not, find a good local independent mechanic and never look back at that dealer.

If yes, read up on the lemon law for your state



no check engine light comes on. as for a coil pack i have not idea what that is

the service dept has no idea what is though they can verify the vibration and droning sound. said there has been no manufacturer notices on this problem.

it is under warranty and i got the gm certification extension. I dont know if i can take it to an independant mechanic or not.