Workspace.Car.Script:6: Expected ')' (to close '(' at line 3), got <eof>?

Like the error says, the script expected you to add a closing ')' at line 5.

If we remove the functions content that you passed as a argument, it becomes more apparent to what's actually going on.

human.HealthChanged:connect(yourFunction 

Here's how to fix your problem

local human = script.Parent:WaitForChild("Humanoid")
human.HealthChanged:connect(function(health)
    wait()
    human.Health = human.MaxHealth
end) -- this closing parentheses requires to be added

I'd encourage you to tab your code properly next time, as it becomes easier to read.

Humanoid.MaxHealth = math.huge
Humanoid.Health = math.huge
print(math.huge) -- inf

Try this!

local human = script.Parent:FindFirstChild("Humanoid")
human.MaxHealth = math.huge
human.Health = math.huge