I wouldn’t give up on those 18” Amfleets in the set, but before I get into that I’ll Provide some alternatives. Prior to some major changes on mylayout about a year or so ago, I predominantly ran 15” & 16” Passenger cars. I’ll list the options and score their: (Q)general quality(I.e. aesthetics, durability, reliability)
(P)the current prices for them in the market
(F)frequency/ability to find a
One=bad, Five=Very good . A score of all 1’s would mean: poor Quality, high/ unreasonable prices, rarely available to buy. If you decide you want MTH 16” Amfleets, I have some phases 3 & 4 in VG to LN condition from which I’m willing to part.
Without further adieu!
MTH Railking Amfleets: 16”, made in a variety of phases Q=4, P=3, F=5
MTH Railking “Misc.” Amtrak Passenger cars: 16”, MTH made a number of Passenger cars that weren’t prototypical Amtrak but decent Q=4, P=4, F=4
K-line Amtrak Horizons: 15”, phase III paint, aluminum body, pop up on eBay every now and then. My favorite 15-16” Amtraks hands down Q=5, P=3, F=2
Lionel Amtrak baggage car- recent make , possibly 2018? 13.5” long, good baggage for 15-16” coaches Q=5, P=2, F=3
MTH Railking Superliners-16 11/16” long, made in Ph III & Ph IV Q=5, P=3, F=4
Lionel Aluminum Amtrak Passenger cars: from early 90s, easiest to find. Don’t really care for them mainly b/c I don’t like “people strips”/undecorated interiors Q=3, P=3, F=5
Williams Amtrak Amfleets- nice, durable and corrugated aluminum. Interiors undecorated Q=4, P=4, F=4
What is the max. curve diameter on your layout? I have the hhp-8 set(2009)and cab control car, the tolling of those set passenger cars is the same as the various Amtrak paint livery phases of 18” Amfleets being offered in the 2022 vol. 1 catalog.
When my max curve diameter was o-42, I ran these Amfleets on it with little issue and I liked how they looked on my layout. I think they can run on o-36. They matched well with a variety of Amtrak power- the HHP-8 obviously, MTH AEM-7 and any of my F-40PH Amtrak locos(K-line, MTH & Lionel). However, I have a either a low ability to notice overhang, high tolerance for overhang, or a combo ha.
Hope this helps!