First, I have 2 scripts that work together to get the tanks speed this is 1:

wait(0.35)
script.LastPositionUpdater.Disabled = false

while wait(1) do
	local Plr = game.Players.LocalPlayer
	local Tank = game.Workspace:FindFirstChild(""..Plr.Name.."'s_Tank")
	local speed = (Tank.Hitbox.Position - script.LastPosition.Value).magnitude
	print(speed)
	Tank.Hitbox.TankSpeed.Value = speed
end

this is 2:

while wait(1) do
	local Plr = game.Players.LocalPlayer
	local Tank = game.Workspace:FindFirstChild(""..Plr.Name.."'s_Tank")
	script.Parent.LastPosition.Value = Tank.Hitbox.Position
end

What they should do is get the speed of the tank in studs per second, it doesn't work or I dont think it does because what the script is outputing doesn't look like what the tank is really going. Here's an example, you can see by the texture in the baseplate that tank is going atleast 1.5 studs per second atleast 1 stud per second even, but the output is showing lower numbers: https://gyazo.com/8a5e5dc9e0c82341c68ae2f65a354b9e