When I was in the Hertz NYC rental, I listened exclusively to MP3s from my USB thumb drive. It sounded best when the car was parked. Maybe a few peaks to the frequency response, but overall, not too bad. When I was moving, as I had suspected, the road noise made the system sound rather thin at the low end. I didn't notice much harshness from my MP3s, so maybe that's a problem at the source. Next time maybe I'll try listening to XM a bit, but their bitrate is so low I though that would not really be a good test of the LEAFs system.
I wonder if they could apply some extra bass automatically as speed increases so it would sound better when in motion?
Also do the LEAF receive HD radio?
Looks as if I might ultimately have to do something with a sub to get the low end to sound right. A Focal mini-sub under the front seat did the trick in my Camry, however that spot is already taken in the LEAF!