Low humming or howling noise sounds like coming from engine compartment. This has been a persistent problem that the dealership has not figured out after full diagnostics etc. Typically only in warmer months, especially in the heat of summer. It can also happen in moderate temps if in stop and go traffic or a long period of idling. When driving the tachometer is around 2800 rpm, and I can make it go away by speeding up or slowing down a bit, to above 3000 rpm or below 2700. Sometimes after awhile the humming doesn't stop regardless of my speed or RPM's. The dealership confirms its not the wheel bearings, tires or brakes. When its hot out, I have been able to recreate the problem to show the dealership, by driving up a hill in 2nd gear (first I drove around for 30 min or so to make sure the car was in a state where it was intermittently humming). Dealership thinks it may be an engine valve issue. Any of you fellow ODY's experienced this? BTW, I have the Honda towing package and have wondered if it could be the automatic transmission (ATF) coolers, but my research hasn't come up with this as an issue. This happens with / without A/C on, and turning or driving straight has no effect. Otherwise the car operates normally.