The latest iteration of Griffin's TuneFlex Aux line of combination car mounts/chargers/audio-out accessories is TuneFlex Aux Handsfree ($50), which uses a decidedly un-Griffin-like workaround to deal with the challenge of offering both audio output and handsfree car phone features. Unlike prior TuneFlex Aux models, which actually used the line-level outputs from iPods and iPhones for peak sound quality, TuneFlex Aux Handsfree uses the iPhone's…