IHC makes a decent passenger car. The main issue is the truck mounted couplers. If you add some weight to the cars, metal wheels and body mounted couplers, they will run well for you. Just make sure you have large curves and don't run them through small switches. The Detail isn't as good as Walthers or Branchline, but they are nice enough.
They have the Kadee bolster replacement kit that replaces the truck mounted NMRA couplers with Kadee's. I've also replaced the wheels with 36" Proto wheels and added extra weight to each car.