Wow, that is strange. I've used 2 phones -- Droid3D and the iPhone 5 in the SR5 and they both sound really thin. Used the Droid in my 2010 F-150 and nobody had difficulty in hearing or understanding me.
Definitely strange - the complaint I get in the Ford is that it sounds like I'm in a wind tunnel. All windows up at normal highway speed. The Toyota is apparently nice and quiet when it comes to background noise.
iPhone5 in both.