Single N₁ and N₂ vehicles with fluted brake drums for parking brakes cannot be inspected on roller and plate test benches or in test drives. Electric parking brake systems cannot be tested on roller and plate test benches or test drives, and wheels cannot be turned on lifts to inspect for damages or bearing wear. Some vehicles have hydraulic braking systems with brake fluid reservoirs not accessible without dismantling or special tools, requiring removal of covers, fasteners, and screws to access brake fluid for inspection. PTI inspection provisions require updating to address these vehicle design variations.