You could potentially try to use a ProximityPrompt instead to check that way if the Player is the owner of that certain vehicle? You’ll need to pass something to check though to make sure that they are the true owner
What you could potentially do, is create an ObjectValue for each Vehicle so that it keeps track of who is actually the Owner of that certain Vehicle
An ObjectValue is basically just a value that can be stored as an object
local ProximityPrompt = script.Parent.ProximityPrompt
local Seat = script.Parent.Seat
local PlayerCheck = script.Parent.ObjectValue
ProximityPrompt.Triggered:Connect(function(Player) --The first parameter is the player who triggered it
if PlayerCheck.Value == Player then --This checks if the Player is equal to the Object's Value (Or the Owner)
Seat:Sit(Player.Character.Humanoid)
end
end)