Roadworthiness or street worthiness is an ability of a car, bus, truck or any kind of automobile to be in a suitable operating condition or meeting acceptable standards for safe driving and transport of people, baggage or cargo in roads or streets, being therefore street-legal A certificate of roadworthiness shows that your vehicle's safe enough to be used on public roads A roadworthy is required whenever a vehicle's sold, if it's being re-registered, and to clear some defect notices.