4.1. The lengths referred to in section 4 do not include the safari bumper that does not exceed by 30 cm the front of a motor vehicle or the bike-rack that does not exceed by 1 m the front of an articulated bus.
The same applies to the aerodynamic system located at the rear of a road vehicle, provided(1) any part of the system located at 1.9 m or less from the ground does not exceed by more than 30.5 cm the rear end of the vehicle;
(2) any part of the system located at more than 1.9 m from the ground does not exceed by 61 cm the rear end of the vehicle.