Yes.
Make the vehicle not a vehicle until the player interacts with it.
For one, there’s no reason for it to sit there unless something needs to use it as a vehicle, so it should really never just be a vehicle.
For 2, you aren’t going to get the current physics engine - chaos - to behave right no matter how blue in the face you turn, mostly because even thohgh they pushed it to prod it is so raw that if it were a cow it would still moo.
And partially, because the player capsule’s movement component AND/OR the physical animation component are essentially unstoppable forces capable of spinning around earth to reverse time. Yep, is it a bird? Is it a plain? No. Its the unreal character capsule.
With 4.x in a custom build and the latest physX dll (which is not included on stock engine), you can put some time into getting Mass and other aspects to be respected (however note that whatever you do, the physics are still more “bouncy” than reality. Unexplicably so perhaps).
So, to “fix” a player or even a projectile from being able to rock or sway a vehicle, your easiest solution is to not have a vehicle to deal with unless you have to.
Same applies to any physics. And For any engine, really.
Unless something is being interacted with and requires simulation, it shouldn’t even be the type of actor which can simulate.
In the case of “player vs car” your best bet is to just disable the player by proximity in some way.
Doesn’t necessarily mean you need to make it ragdoll when the car is approached, but if you turn off input when the vehicle is touching, and the vehicle is moving, the physics will do some of the rest.
The basis of the problem originates from the movement input force being applied and used to calculate against the vehicle (which for human vs car is essentially an impossibility) so you can eliminate that part alltogether a few frames before impact and save yourself from having issues.
I’d suggest doing this for anything the player approaches.
Meaning theres no reason to move forward against a wall, so why bother applying the input in that direction?
For games that make some use of physics, this can be beneficial. Preventing you from pusing objects around unless they are specifically tagged into a collision channel…