Function module for classifications/characteristics

Can anyone suggest a function module or bapi I can use to get values for characteristics.

We are using characteristics to store additional information about fleet vehicles that are not included as standard SAP fields.

At the moment, I am using a couple of database calls, using tables 'CABN' and 'AUSP' to find values of these characteristics for a particular vehicle.

There must be an easier way, using a function module or bapi. Could anyone shed some light?