As far as things to look for, on high mile winter cars the front frame rails where they meet the floor next to the cats need to be looked at. ALL chargers and Challengers should have the inside of the rails oil sprayed with boeshield or crown, or other similar rust protection that you can wash out and reapply if you drive in rain or snow. As far as hellcat durability I would not worry a whole lot, we just went to Radford racing school and beat the tar out of Redeyes and Demons, the redeye all had about 15,000 track miles and who knows how many sets of tires and were all tight non rattling cars. Average fuel milage was in the 5s for the redeye and 3 for the Demons. So they were floored a lot. We ran everything hard, caught air in the Essex, well into triple digit, with the air on and not one issue. The 4 Demons made 1/8 and 1/4 mile passes one right after the other, never shut down just pass after pass, 3 of them ran 9s best was a 9.74 at 139, just Joe average driving, not a racer. My wife went 10.
17 at 135....first time she was ever on a drag strip. The demons were on nittos and had the 305 front tires on, both front seats, a mini cage and racing harnesses, and no race gas. To say I was impressed is an understatement. Anyway the average owner will never beat them like that, buy a low mile hellcat with confidence.