A navigation device arranged to give navigation instructions to a driver of a vehicle, said device comprising: a route calculation module that is arranged to determine a route from an origin to a destination; an instructions module arranged to produce a set of base instructions for the driver so as to enable the driver to go the determined route; a driver recorder arranged to record at least one driving behaviour parameter of said driver, a profile module arranged to build up at least one profile, wherein said profile module comprises: an environmental profiler arranged to continuously sample environmental parameters representative of road conditions and/or weather conditions to build up an environmental profile; and/or a route profiler arranged to continuously sample route parameters representative of traffic conditions of the determined route to build up a route profile; a driver profiler arranged to build up or update at least one driver profile using said recorded at least one driving behaviour parameter; and a profile-to-instruction translator arranged to convert the set of base instructions into a set of output instructions depending on said at least one driver profile, characterised in that: the driver profiler is further arranged to: use the sampled environmental and/or route parameters from the profile module to determine whether a recorded at least one driving behaviour parameter is suitable for use in building up or updating the at least one driver profile, and, when indicated by the sampled environmental and/or route parameters, to use the recorded at least one driving behaviour parameter to build up or update said at least one driver profile. a route calculation module that is arranged to determine a route from an origin to a destination; an instructions module arranged to produce a set of base instructions for the driver so as to enable the driver to go the determined route; a driver recorder arranged to record at least one driving behaviour parameter of said driver, a profile module arranged to build up at least one profile, wherein said profile module comprises: an environmental profiler arranged to continuously sample environmental parameters representative of road conditions and/or weather conditions to build up an environmental profile; and/or a route profiler arranged to continuously sample route parameters representative of traffic conditions of the determined route to build up a route profile; a driver profiler arranged to build up or update at least one driver profile using said recorded at least one driving behaviour parameter; and a profile-to-instruction translator arranged to convert the set of base instructions into a set of output instructions depending on said at least one driver profile, characterised in that: the driver profiler is further arranged to: use the sampled environmental and/or route parameters from the profile module to determine whether a recorded at least one driving behaviour parameter is suitable for use in building up or updating the at least one driver profile, and, when indicated by the sampled environmental and/or route parameters, to use the recorded at least one driving behaviour parameter to build up or update said at least one driver profile. the driver profiler is further arranged to: use the sampled environmental and/or route parameters from the profile module to determine whether a recorded at least one driving behaviour parameter is suitable for use in building up or updating the at least one driver profile, and, when indicated by the sampled environmental and/or route parameters, to use the recorded at least one driving behaviour parameter to build up or update said at least one driver profile. use the sampled environmental and/or route parameters from the profile module to determine whether a recorded at least one driving behaviour parameter is suitable for use in building up or updating the at least one driver profile, and, when indicated by the sampled environmental and/or route parameters, to use the recorded at least one driving behaviour parameter to build up or update said at least one driver profile.