Which of the following is NOT a reason for impounding a vehicle?

Impounding a vehicle for reasons such as being evidence of a crime, being reported stolen, or being part of a crime scene is associated with instances where the vehicle is directly linked to illegal activities or criminal investigations. In these situations, police may need to secure the vehicle for further investigation, preservation of evidence, or to return the stolen property to its rightful owner.

However, when it comes to improper parking, while it may warrant a citation or ticket, it does not involve criminal activity or criminal investigations. Instead, improper parking is typically dealt with by law enforcement through fines rather than impounding the vehicle. Therefore, it stands out as the situation that does not justify the impounding of a vehicle, making it the correct answer in this context.