What is a key number (KBA, HSN/TSN)?
The key numbers (KBA) are the best tool to find out the most common data of the vehicle.
The amount of related data varies slightly from car manufacturer to car manufacturer, but is often sufficient to identify most spare parts.
The key numbers consist of two details in total, namely points 2.1 and 2.2 in your vehicle documents.
2.1 indicates the manufacturer (e.g.: 0005 = BMW) ; 2.2 indicates the model and the engine.
With VAG (VW/AUDI), the so-called PR numbers often come into play. These can only be found out via the sticker in the vehicle and logbook or via the chassis number and usually differ depending on the equipment and engine within a model.
The chassis number makes it possible to see all the spare parts of the vehicle. The number always has 17 digits and can be found in the vehicle documents under point "E".
Some detailed data about the vehicle (such as production date, equipment variants) can also be determined via the chassis number. Contrary to what many people think, we cannot determine any personal information by means of the chassis number. Therefore, by transmitting your chassis number, you are not taking any risks.
Here is an extract where you can find the named numbers in your vehicle registration document: