Thanks so much for your detailed help.
The Print String attached to Event Possessed does report that the car pawn is possessed when I enter the game. It prints the possession report twice, in fact.
However, the Print String attached to EnhancedInputAction IA_Throttle does not report anything when I press any of the defined throttle buttons.
In your first blueprint graphic, should I assume that the output of the Add Mapping Context node connects to the input of the Cast To ChaosWheeledVehicleMovementComponent node which starts out connected to the output of Event BeginPlay before I create and connect the Enhanced Input Local Player Subsystem and Add Mapping Context nodes (which aren’t there in the SportsCar_Pawn BP when I open it in the editor)?
Here’s how I connected it up after creating the nodes (ignore that the Mapping Context isn’t set in this example):
ETA: is it possible that inputs are bugged in 5.2.1? I was watching a tutorial using the same vehicle demo level where the input controls “just worked” upon first load, but they were in engine 5.1.