Well car category wise it is certainly an upgrade, whether one likes the car or not is a personal preference. I for one would not have taken it as it is a crappy ride and a fuel guzzler, but that's an aside.

For the car category, the staffer may have been confused themselves. The CTS is usually offered as an LCAR, but so is the ATS though I agree it would fit better in PCAR.

As far as insurance goes, I was actually talking about roadside protection and passenger insurance as my rentals also always include LDW and LIS. The Roadside protection can come in handy, as tire damage isn't covered by LDW and given the rubbish (e.g. big shreds of truck tires) on US Highways it saved me almost 500$ in cost the last time when I had damage to some Pirelli 235/45 tire on a loaded Volvo S80 where just the tire was 330$ plus labor and all.