I have a 2008 Civic EX Coupe (not Si) with 78,000 miles, which I've owned since new and I've maintained it according to Honda Specs. Lately, as the weather has turned cold (i.e., near freezing), the idling engine sounds hoarse or deep, and this sound is accentuated with front suspension travel. In other words, when the front suspension compresses ( e.g., crossing through a dip in the road), the throaty sound of the engine is worse. This quirky engine sound goes away when the block is fully heated, say after a good 20 minutes of driving. Incidentally, the performance of the engine seems never to be compromised, and the mileage is still Civic-like.

Any thoughts, or is my car possessed?

 

Could be a motor mount, I've heard about them doing strange things in 8th gen's. It would make sense that it goes away after 20 min because it takes this long for everything in the engine compartment to get warmed up, warm rubber is more flexible so it better absorbs the engine vibrations if that makes sense. It's not the engine itself making more noise, it's the mounts (or a mount) transferring more vibrations to the fame when the rubber is cold. Also makes sense with it being worse when you go over dips, when you compress at the bottom of the dip the motor is compressing on the mounts too transferring more vibration.

Just a guess..

 

Your diagnosis of my problem was correct. They found that the upper left (passenger side) mount was severely compromised. When they removed it to replace it, they discovered that it was cracked. This flaw could not, however, been seen until it was removed.

Thanks for your help.