alt Hacker NewsThat flies in the face of what I understand is true about diplomatic immunity. Citation required.
As a less extreme example, diplomats can and DO park their vehicles illegally: in No Parking zones, Handicap Only zones, and blocking fire hydrants. Diplomat plates render the police unable to ticket them. It's civil not criminal courts, but for the exact reason that they are immune to our laws.
A diplomatic vehicle that is a safety hazard can be towed. A city/state cannot enforce any fines, but they can definitely clear any safety or traffic related issues.
I would start with Vienna Convention on Diplomatic Relations and go from there.