You might could try increasing the net update frequency, along with setting Component Should Update Physics Volume to true on the vehicle movement component. Depending on your multiplayer setup you might need to also Enable Physics On Dedicated Server on the skeletal mesh component as well. You could also tool around with Physics Transform Update Mode and try setting it to Simulation Updates Transform Component. Net load on client also…
The multiplayer vehicles are almost entirely simulating physics over the network so it’s very difficult, but it can be done for sure and smoothly at least as far as 5.1. Beyond that you might be facing a replication issue. I could say that’s a very likely issue if you’re just passing input axis values directly to add input?