There are certainly positive comparison features for both the RNS315 and RNS-510. The most visible positive for the RNS-510 is its larger display. But it costs much more than the RNS-315. HD radio is built into the RNS-510 (not sure about the RNS-315), and live traffic is available on the RNS-510 if you subscribe to it.



) and couldn't really find a comparison of the two units. I'm looking at getting a new 2012 GLI (probably) and am curious why they don't include a few features (live traffic, HD Radio) and was wondering if this was built-in to the RNS-510? Why would someone choose the 510 over the newer (apparently faster) 315?
