An assessment is required following modifications to your vehicle. When must this be performed?

The requirement for an assessment after vehicle modifications is rooted in ensuring that the vehicle remains safe and compliant with traffic regulations. In Germany, modifications can potentially alter the vehicle's performance or safety features, which is why an assessment is typically needed.

The correct combination of answers indicates that the assessment should be done promptly after modifications to verify compliance immediately, but it is also relevant during the next scheduled inspection or upon request from the registration authority. This means that while the immediate assessment is crucial, the ongoing compliance checks at regular intervals or upon authority demand are also important to maintain safety and legality on the roads.

In summary, immediate assessment following modifications ensures safety right away, while the other two options provide for ongoing compliance check mechanisms as per German traffic laws.