How do I make a car? (I'm new with making cars)

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#1

So, I’m new to making cars and I’m wondering if I’m doing this wrong or if there is an easier way to accomplish car physics. Currently The car can’t go backwards, floats in air (I already know why, but don’t know the solution.), and is just very buggy. Any help and tips will help.

Code:

local Seat = script.Parent.VehicleSeat
local acceleration = 0
local AmountofTires = 0

local CollectionService = game:GetService("CollectionService")

function UpdateSpeed(Part)
	local Deceleration = AmountofTires / 4
	local Rotation = .5 * acceleration
	local GOOOO = acceleration / 4
	local Weld = Part:FindFirstChildWhichIsA("ManualWeld")
	if Seat.ThrottleFloat == 1 then
		Part.AssemblyLinearVelocity =  -Part.CFrame.LookVector * Seat.Throttle * GOOOO * AmountofTires
	else
		Part.AssemblyLinearVelocity =  Part.CFrame.LookVector * Seat.Throttle * GOOOO * AmountofTires	
	end
	Weld.C1 = Weld.C1 * CFrame.Angles(0, 0, math.rad(Rotation))
end

while true do
	wait()
	AmountofTires = 0
	AmountofTires += #CollectionService:GetTagged("Tire")
	local Deceleration = AmountofTires / 4
	if Seat.ThrottleFloat ~= 0 then
		if Seat.ThrottleFloat == 1 then
			if acceleration < Seat.MaxSpeed * Deceleration then
				acceleration += 1 * Deceleration
			end
		else
			if acceleration < -Seat.MaxSpeed * Deceleration then
				acceleration -= 1 * Deceleration
			end
		end
	else
		if acceleration > 1 then
			acceleration -= 1
		end
		if acceleration < 1 then
			acceleration += 1
		end
	end
	local Tires = {}
	for _, New in pairs(CollectionService:GetTagged("Tire")) do
		table.insert(Tires,New)
	end
	for _, New in pairs(Tires) do
		if New:FindFirstChild("WheelWeld") then
			UpdateSpeed(New)
		end
	end
end