2.9 EP Player's Car (Banshee) from Gray Imports
I found some notes that might help clear up some confusion but can't quote them properly because the topic is locked.
It looks like EP is applied to the player's car right at the end of the mission as part of the mission cleanup routines on V1 and V2. Shortly before that there's a code that clears all immunities. Wait until the mission is completely over and the actor's car should be EP unless it is wrecked.
The vehicle the player is driving during the last few meters as the target is approaching the Banshee is recorded by the script, and after the mission is over (success or failure) the proofing is applied if the vehicle is not destroyed. I ran several tests with v1 and v2 scripts and managed to proof the PCJ, Banshee, a Euros I spawned at the bottom of the stairs, and a car I grabbed from the street (not all during the same attempt though).
The loop that records the player's vehicle begins after the target makes the final turn around the containers and starts heading directly at the Banshee. The loop stops when he enters the Banshee.
If the player enters the Banshee before the loop begins then the vehicle will not be proofed.
Gray Imports: Player's Car; 0, 1, 1, 0, 0 (entering the mission sphere at the docks)
Gray Imports: Player's Car 2; 0, 0, 0, 0, 0 (as the target approaches the Banshee)
Gray Imports: Player's Car 2; 0, 0, 1, 0, 0 (when mission is over)
The images below show where the target is located when the loop begins from slightly different angles.