Method for automatically assessing performance of a driver of a current vehicle for a particular current trip, wherein updated current-trip driving data sets are repeatedly read from the vehicle, wherein the current vehicle is not arranged to itself record data corresponding to a basic parameter set, said current-trip data sets each comprising data from at least a predetermined set of extended driving data parameters collected by the current vehicle or by a portable electronic device arranged in the current vehicle, and wherein new such current-trip data sets are read from the vehicle at consecutive observation time points separated by at the most a predetermined observation time period, wherein each of said current-trip driving data sets is read as an instantaneous readout or as an average value read across a certain averaging time period of at the most 5 second of length, and wherein the method comprises the steps of a) collecting previous-trip driving data sets, observed at a plurality of different observation time points, for a plurality of different previous trips made by a plurality of different drivers and a plurality of different vehicles and communicating said previous-trip driving data sets to a server (150, 160), where each of said previous-trip driving data sets is observed at a respective one of said plurality of different observation time points, where said parameter values of the previous-trip driving data sets are each read either as a respective instantaneous value or a respective average value read across a certain respective time period of at the most 5 seconds of length, said previous-trip data sets each comprising parameter values for both said set of extended driving data parameters and a predetermined set of a qualified parameter set, said qualified parameter set comprising the parameters of a basic parameter set and instantaneous vehicle energy consumption; b) grouping said previous-trip driving data sets into basic historic groups of such sets, based upon a basic driving data set similarity measure, said basic similarity measure being arranged to take values for said basic parameter set into consideration, and calculating the value of a respective group performance parameter for each such basic historic group; c) further grouping said previous-trip driving data sets into extended historic groups of such sets, based upon an extended driving data set similarity measure, said extended similarity measure being arranged not to take all values for said basic parameter set into consideration that are taken into consideration by the basic similarity measure; d) for each of said current-trip data sets, mapping the current-trip data set in question to at the most one particular of said extended historic groups, based upon an extended group conformity measure between a driving data set and an extended historic group; and e) calculating a current-trip performance parameter based upon the said group performance parameter values of respective basic historic groups corresponding to previous-trip driving data sets comprised in the extended historic group to which a current-trip data set was matched in step d, and in that the current-trip driving data sets do not comprise at least one parameter of the basic parameter set. a) collecting previous-trip driving data sets, observed at a plurality of different observation time points, for a plurality of different previous trips made by a plurality of different drivers and a plurality of different vehicles and communicating said previous-trip driving data sets to a server (150, 160), where each of said previous-trip driving data sets is observed at a respective one of said plurality of different observation time points, where said parameter values of the previous-trip driving data sets are each read either as a respective instantaneous value or a respective average value read across a certain respective time period of at the most 5 seconds of length, said previous-trip data sets each comprising parameter values for both said set of extended driving data parameters and a predetermined set of a qualified parameter set, said qualified parameter set comprising the parameters of a basic parameter set and instantaneous vehicle energy consumption; b) grouping said previous-trip driving data sets into basic historic groups of such sets, based upon a basic driving data set similarity measure, said basic similarity measure being arranged to take values for said basic parameter set into consideration, and calculating the value of a respective group performance parameter for each such basic historic group; c) further grouping said previous-trip driving data sets into extended historic groups of such sets, based upon an extended driving data set similarity measure, said extended similarity measure being arranged not to take all values for said basic parameter set into consideration that are taken into consideration by the basic similarity measure; d) for each of said current-trip data sets, mapping the current-trip data set in question to at the most one particular of said extended historic groups, based upon an extended group conformity measure between a driving data set and an extended historic group; and e) calculating a current-trip performance parameter based upon the said group performance parameter values of respective basic historic groups corresponding to previous-trip driving data sets comprised in the extended historic group to which a current-trip data set was matched in step d,