 We too have one of the vehicles which makes an incredibly annoying intermittent buzzing sounds.  The dealer has blown us off, pretending like the sound is normal, but it's totally unacceptable.  Toyota customer support has been no help at all! Thanks to the Internet, we know we are not crazy or alone like Toyota wants us to think we are.  I STRONGLY recommend reading these forums before buying a Highlander or Sienna:http://www.toyotanation.com/forum/333-3rd-generation-2014/1077937-weird-vibrating-buzzing-noise.htmlhttp://www.siennachat.com/forum/193-problems-maintenance-repair/228201-2015-xle-sienna-humming-buzzing-noise-dash.htmlhttp://toyotaowners.net/toyota-forum/showthread.php?t=24778http://www.aboutautomobile.com/Complaint/2015/Toyota/Highlander/10715419http://www.toyotanation.com/forum/333-3rd-generation-2014/1092585-new-2015-ltd-strange-sound-coming-dash-area.html