What feature must all vehicles made after May 23rd, 1970 have?

All vehicles made after May 23rd, 1970, are required to have a mechanical parking brake that can hold the vehicle on a 20% grade. This requirement is significant for ensuring safety, as it prevents vehicles from rolling away when parked, especially on inclines. A mechanical parking brake, also known as an emergency brake, provides a necessary backup to the main braking system, allowing drivers to secure their vehicles effectively.

The ability to hold a vehicle on a 20% grade ensures that the parking brake is robust enough to handle more challenging parking situations. This is particularly crucial in areas where steep inclines are common, reducing the risk of accidents caused by vehicle rollaway incidents. Having this standard enhances overall vehicle safety for drivers and pedestrians alike, making it a fundamental feature mandated by vehicle safety regulations.