Are there multiple body styles? At ATL, they insisted what looks like the 2013 model was 2014, but there was clearly a 2014 new body. I like the new one quite a bit having been given an LTZ (looks different than OP's 2014 Impala LTZ).

Notable features I remember were the lane drifting warning, blind spot/lane switch warning, front collision warning, and it definitely had USB. Overall a great rental and I would definitely rent again given the chance.