No. Wrong. Liar.
The iTrip is terrible. My stereo is fine. Or, maybe you're right. Maybe my stereo "detects" that I'm using an iPod instead of CDs, so it makes it sound bad. Yeah, that's the ticket. That would explain why my iPod sounds like trash with the FM transmitter, and CDs sound awesome. It's probably some sort of "M$ Conspiracy" to get iPods out of cars. But wait? Then why would it sound so nice with my tape adapter in my old car?! *sarcasm sarcasm*
"Playing around with the stations" is about as productive as sticking your thumb up your ass. The product sucks, it's over-hyped, the quality = balls. If you're content with hissy sounding, mid-range (no highs, no lows), dropouts and mono 56kbps mp3 filles, then yes, the iTrip is sweet and the quality is unsurpassed.
And the "engine noise" thing? I don't even know how to answer that one...
I've read the manual many times. Mostly because I didn't think it was possible for a $40 product to suck so much. I even read about modding it on the net, to get an increase in signal strength, hoping that it would save the product from it's lackluster 3ft. broadcasting radius...
iTrip stinks. Don't believe me? I'll send you mine. That's my guarantee.