what recourse do i have against city banning me from parking certain vehicle in my driveway?

There are 6 of us who drive small special needs school buses, and have been allowed, by our employer, to park overnight at home, for as long as 29 years. Now our city has rewritten parking ordinance, banning all vehicles over 8000 lbs. gross vehicle weight rating, from parking in residential areas unless performing a service. The original ordinance was enacted in 1995, never enforced, and we have never been notified until now. Does implied consent apply in this situation?
(Consent made evident by signs, actions, or facts, or by inaction or silence.)
Some of us have received other citations, such as camper on driveway not allowed, while the bus was sitting right next to it, and didn't get cited for oversized vehicle (bus) not allowed. How else can we fight this?