What you really want to do is to picket in front of the dealership.  Laws vary and can depend on place you want to picket. You are given Freedom of Speech rights under our Federal Constitution and i am sure that the Colorado Constitution mimics this right "locally."   But the law does not protect free speech if it is meant to harm or incite a riot. Now, local laws can regulate time, place, and manner for picketing. And they may also require a permit.  Check with your town board or police department. Remember that you may be threatened with defamation by the dealership but truth is always a defense.  Just be careful what you say and how you say it.  Good luck.