Should I be worried?

[Dcting]

So I have a new 08 with 634 miles on it and everytime i hit the road for a good bit and turn off my car, I get knocking/pinging from the exhaust. Yes, I have searched and wiki'ed the physics behind it and am still a little confused... Yes, I use premium 93 octane gas. Should a brand new car have this issue? The car is freakin 2 months old only!!! Shouldn't this only be an issue on older models that use lower octane gas? Sorry, if this topic seems pointless, but was just wondering if anyone else has this issue?

Feedback and opinons greatly appreciated.

Thanks,
DT

[i_audi]

Do you get your gas at the same place each time? Also try switching brands.

[minameismud]

imo, this is normal. ever car/truck i've had does this, and it's not just the exhaust. any part that gets hot (200+ F) cools down. while heating makes components expand, cooling causes them to contract. it's this contracting motion of two parts at the same time that are connected that causes the sounds. kinda like how your home's floor squeaks, but instead of your ass causing the motion, it's thermodynamics.

[vegascoop]

This does not sound normal. Have the dealer check it out.

[nick71692]

mynew 08 does the same thing, as previously stated it sounds like the exhaust cooling down. as long as it isnt from my engine it doesnt bother me. my 05 does the same thing, so does my dads 08 750i

[Grk_A4]

Yeah my 07 does the same thing. It's normal.

[06A420T]

Its just the exhaust expanding and contracting my car does it so does my gto its really crazy here cause its 115 outside day time so its loud on my gto haha.

Jason