Who is allowed to issue a certificate on the testing of a speed limiter?

You answered correctly that the certificate for testing a speed limiter can only be issued by the vehicle manufacturer officially recognized for this task, or by a workshop authorized by an authority. This is because these entities have the proper expertise, official recognition, and legal permission to ensure that the speed limiter is tested accurately and complies with safety regulations. Not all workshops can perform this task, as it requires specific authorization to guarantee the test's validity and legal acceptance. This rule helps maintain safety standards and ensures that speed limiters work correctly to prevent overspeeding in commercial vehicles.