I used to enjoy the swaying cars, but in time, my flat wheels were not alone. I found fast angle wheels needed to sit tighter to the frames..and tracked different. Seemed to progress over time too. My modern stuff has little bolster play, and often has smaller fatter wheel flanges in comparison to my early stuff,. The FA wheels tip the body more like the real thing, but the angle is harder, the truck motion is snakey; wavey, off center and twisty when not fully in tandum ,,... the motions timing strikes me funny, they never tip to the outside till fully out off curves, and they climb easy if loose at the trucks pivot too.
This is no biggie, kinda slipped by really, but I did notice at some point.
For fun I'd like to see the action on some trucks with fixed axles, bearings in the wheels and no need of the hard fast angle for diffirential purposes. Small enough bearings arent much of an issue anymore.
I like the motion of the old cars and am guessing its the "water level" pull behind that, but man those things are big loads of raw axle friction to pull too. I'd guess 25% less efficient at least, plus half are cast metal, lol.