Swiss EuroCity services continue to run on the Rhine route, and remain some of the highest quality trains on the route. Starting at Hamburg and, in the old days, Amsterdam, and serving Chur among other places, they'd really add to the LR route as well as providing their desperately needed function: extra rolling stock for Luzern. These are the coaches as they looked in 1997 1st class 2nd class 1st class panorama: Restaurant: Full rake with a different restaurant variant: Modern look: As this would primarily be an addon for Luzern, a 420 would make sense, as it could run any sort of service on that - and any future SBB - route.
If you want to make it realistic as possible you need the German and Austrian capable variant of 420 the 421. Feature of the locomotive it has 1.95m pantograph Metalized Carbon or Carbon strip for 15kv 16.7hz DB Netze ÖBB Infra PZB systems due to Swiss pantograph being 1.45m Carbon/Copper Strip 15kv 16.7hz. Since running a Swiss Carbon strip & Italian Copper Strip 1.45m on German and Austrian 15kv OHLE causes the train to lose power.