"create a car with max speed 20, add a function to move the car with w,s,a,d"

local car = Instance.new("Model")
car.Name = "Car"
car.Parent = game.Workspace

local body = Instance.new("Part")
body.Name = "Body"
body.Parent = car
body.Size = Vector3.new(4, 2, 8)
body.Position = Vector3.new(0, 1, 0)

local wheel1 = Instance.new("Part")
wheel1.Name = "Wheel1"
wheel1.Parent = car
wheel1.Size = Vector3.new(2, 2, 2)
wheel1.Position = Vector3.new(2, 0.5, 3)

local wheel2 = Instance.new("Part")
wheel2.Name = "Wheel2"
wheel2.Parent = car
wheel2.Size = Vector3.new(2, 2, 2)
wheel2.Position = Vector3.new(-2, 0.5, 3)

local wheel3 = Instance.new("Part")
wheel3.Name = "Wheel3"
wheel3.Parent = car
wheel3.Size = Vector3.new(2, 2, 2)
wheel3.Position = Vector3.new(2, 0.5, -3)

local wheel4 = Instance.new("Part")
wheel4.Name = "Wheel4"
wheel4.Parent = car
wheel4.Size = Vector3.new(2, 2, 2)
wheel4.Position = Vector3.new(-2, 0.5, -3)

local maxSpeed = 20
local throttle = 0
local steering = 0

local function moveCar()
    local speed = throttle * maxSpeed
    body.CFrame = body.CFrame + body.CFrame.lookVector * speed
    body.CFrame = body.CFrame * CFrame.Angles(0, math.rad(steering), 0)
end

game:GetService("UserInputService").InputBegan:Connect(function(input, gameProcessed)
    if gameProcessed then return end
    if input.KeyCode == Enum.KeyCode.W then
        throttle = 1
    elseif input.KeyCode == Enum.KeyCode.S then
        throttle = -1
    elseif input.KeyCode == Enum.KeyCode.A then
        steering = -1
    elseif input.KeyCode == Enum.KeyCode.D then
        steering = 1
    end
end)

game:GetService("UserInputService").InputEnded:Connect(function(input, gameProcessed)
    if gameProcessed then return end
    if input.KeyCode == Enum.KeyCode.W then
        throttle = 0
    elseif input.KeyCode == Enum.KeyCode.S then
        throttle = 0
    elseif input.KeyCode == Enum.KeyCode.A then
        steering = 0
    elseif input.KeyCode == Enum.KeyCode.D then
        steering = 0
    end
end)

game:GetService("RunService").Heartbeat:Connect(function()
    moveCar()
end)