I have a 2008 Hyundai Elantra, and recently I started hearing like a helicopter noise, occasionally, when Ishifted my car in reverse and sometimes when I wait at a stop light. It goes away when I take my foot off the break. I already took it to Hyundai dealer and they couldn't replicate the noise and couldn't find anything wrong with the car. Has anybody else experienced this? Does anybody know what might be causing this?

 

If it only happens when your foots on the brake, then sounds like your ABS system is somehow funky, and the brakes flutter while it's sitting still.

 

That's what I thought too. I asked the dealer and they said there is nothing wrong with the ABS.