How to Rig a Car

Your missing a lot of code from the tutorial idk if you followed the whole tutorial but this was the final code:

local car = script.Parent
local seat = car.Body.VehicleSeat
local body = car.Body.Body

local physicsService = game:GetService("PhysicsService")
local DefaultCollisionGroup = "Default"
local CharacterCollisionGroup = "Character"

local cooldown = 0

local OccupiedPlayer
local OccupiedClientScript

local carClientScript = script.CarClient

local function Cooldown(duration)
	local cooldownTag = tick()
	cooldown = cooldownTag
	delay(duration,function()
		if (cooldown == cooldownTag) then
			cooldown = 0
		end
	end)
end


local function SetCharacterCollide(character,ShouldCollide)
	local group = (ShouldCollide and DefaultCollisionGroup or CharacterCollisionGroup)
	for _,part in ipairs(character:GetDescendants()) do
		if (part:IsA("BasePart")) then
			part.Massless = not ShouldCollide
			physicsService:SetPartCollisionGroup(part, group)
		end
	end
end

local function BodyTouched(part)
	
	if (seat.Occupant or cooldown ~= 0) then return end
	
	local character = part.Parent 
	local player = game.Players:GetPlayerFromCharacter(character)
	if (not player) then return end
	
	local humanoid = character:FindFirstChildOfClass("Humanoid")
	if (not humanoid) then return end
	
	seat:Sit(humanoid)
	OccupiedPlayer = player
	SetCharacterCollide(character,false)
	car.PrimaryPart:CanSetNetworkOwnership(player)
	OccupiedClientScript = carClientScript:Clone()
	OccupiedClientScript.Car.Value = car
	OccupiedClientScript.Parent = player.Backpack
	Cooldown(2)
end

local function OccupantChanged()
	if (seat.Occupant) then return end
	if (OccupiedPlayer.Character) then
		SetCharacterCollide(OccupiedPlayer.Character,true)
	end
	if (OccupiedClientScript.Parent) then
		OccupiedClientScript.Stop.Value = true
		local client = OccupiedClientScript
		delay(3, function()
			client:Destroy()
		end)
	end
	car.PrimaryPart:SetNetworkOwnershipAuto()
	OccupiedPlayer = nil
	OccupiedClientScript = nil
	Cooldown(3)
end

body.Touched:Connect(BodyTouched)
seat:GetPropertyChangedSignal("Occupant"):Connect(OccupantChanged)