That would be a start but imo not enough. If police decide they need to track your vehicle, and can convince a judge of it, and get a warrant, they can place a tracker. Flock and similar systems open more information to them than that process does. They don't get to track you retroactively before the date of the warrant, for one thing.
I have been advised that ... legally ... a tracker placed on your vehicle without your knowledge or permission is abandoned property. You're free to remove it and dispose of it as you wish. Placing it on a government employee's vehicle, while amusing, is probably not the best way to dispose of it.