I drive a convertible and until now the only way to talk at speed with the roof down was with the hideous "the boom" wired headset. Jawbone etc. all failed horrendously.
One day I hadn't connected my plantronics headset and was taking a call with the phone in its cradle, when I realised that the callers voice was coming from the stereo and he could hear me just fine, at 80mph, with the roof down: the phone was on speaker mode.
Amazing, for me its the most compelling reason not to change the s3 for an HTC one