If you copy/post the script here we can help you better. Please put 3 backticks (```) before and after it so it formats properly.
Basically you already have your counter built in when you click your GUI. Every time you click you make your variable add one. For example if you use the variable counter then every time you click have the line counter += 1.
Next is a check to see if counter is 25 (or greater just in case the player gets a couple of clicks in due to lag)
if counter >= 25 then
-- your code here to unanchor the part, I used the variable cantmove
-- that you'll need to identify as your anchored Part in the car)
local cantmove.Anchored = false
end
textLabel:GetPropertyChangedSignal("Text"):Connect(function()
local count = math.round(tonumber(textLabel.Text)) -- round just to be sure (to avoid results like 25.00002)
if count == 25 then
part.Anchored = false
end
end)