A tachograph suitable for connection to a detachable external function module, the tachograph comprising: - a security protected case, - at least one, wired or wireless, function module interface (IFFM1) for secure communication of data between the tachograph and a tachograph data interface of a connected external function module (EFM1, EFM2, EFM3), said external function module comprising at least one function (EF1, EF2, EF3) wherein the tachograph comprises: - means (RECEFM) for recognizing different types of functions of said connected external function module, means (AEFM) for adapting itself for using recognized types of functions of said connected external function module, wherein the recognition of functions and/or adaptation of the tachograph is done, at least partly, automatically when said external function module is connected to the tachograph, wherein the function module interface comprises a mechanical interface consisting of at least one cavity or recess on the outside of the security protected case, wherein the cavity or recess is configured for the external function module being placed therein, and wherein the tachograph is configured to recognize and use at least one of the following functions comprised in said connected external function module: - GPS function - area access payment - arithmetic unit function, wherein the external function is used for calculations, e.g. calculations of time limits for driving time - mobile phone functions - cargo information - motion sensor - crash/event recorder - processor and memory programmable by a user for personalized functions - telematic functions for wireless downloading data from the tachograph or a driver data memory. - a security protected case, - at least one, wired or wireless, function module interface (IFFM1) for secure communication of data between the tachograph and a tachograph data interface of a connected external function module (EFM1, EFM2, EFM3), said external function module comprising at least one function (EF1, EF2, EF3) - means (RECEFM) for recognizing different types of functions of said connected external function module, means (AEFM) for adapting itself for using recognized types of functions of said connected external function module, wherein the recognition of functions and/or adaptation of the tachograph is done, at least partly, automatically when said external function module is connected to the tachograph, wherein the function module interface comprises a mechanical interface consisting of at least one cavity or recess on the outside of the security protected case, wherein the cavity or recess is configured for the external function module being placed therein, and wherein the tachograph is configured to recognize and use at least one of the following functions comprised in said connected external function module: - GPS function - area access payment - arithmetic unit function, wherein the external function is used for calculations, e.g. calculations of time limits for driving time - mobile phone functions - cargo information - motion sensor - crash/event recorder - processor and memory programmable by a user for personalized functions - telematic functions for wireless downloading data from the tachograph or a driver data memory. - GPS function - area access payment - arithmetic unit function, wherein the external function is used for calculations, e.g. calculations of time limits for driving time - mobile phone functions - cargo information - motion sensor - crash/event recorder - processor and memory programmable by a user for personalized functions - telematic functions for wireless downloading data from the tachograph or a driver data memory.