Speedometer Speed Display For Cars?

How would you make your screen gui or surface gui show your cars speed, example, The text says Speed: (This is where the speed goes). Say your going 45 sps (Speeds Per Second) or 45 KMH or 45 MPH, or just 45, how would you get your text to change to your cars speed through a script.

This is easily determined by the vehicleseat's velocity.

For example:

local speed
local driverseat = "driverseat directory"

driverseat.Changed:connect(function()
	speed = math.floor(driverseat.Velocity.Magnitude)/2 -- Divide it by two to get "studs per second"
end)