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, which current-trip driving data sets each comprises data from at least a predetermined set of basic driving data parameters, wherein new such current-trip driving data sets are read from the vehicle at consecutive observation time points separated by at the most a predetermined observation time period, characterised in that 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 seconds of length, and in that the method comprises the steps, performed by a server (150,160), of a) collecting previous-trip driving data sets, each of which is observed at a respective one of 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, which previous-trip driving data sets each comprises parameter values for at least a certain predetermined set of qualified driving data parameters in turn comprising the said basic parameter set, which set of qualified driving data parameters comprises instantaneous vehicle energy consumption, and which parameter values 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; b) mapping each of said current-trip driving data sets to a respective basic historic group of said previous-trip driving data sets using a basic group conformity measure between a current-trip driving data set and a basic historic group of said type, which basic group conformity measure is a measure of how closely the data set in question conforms to the basic historic group in question; and c) calculating an energy consumption-based trip performance parameter value for the current trip based upon a respective energy consumption-based group performance parameter value for each mapped basic historic group; wherein said basic parameter set comprises instantaneous velocity, instantaneous engine rotation speed, instantaneous velocity change and instantaneous engine rotation speed change, and/or the basic parameter set comprises instantaneous motor load, instantaneous energy consumption, instantaneous motor load change and instantaneous energy consumption change, and in that these parameter values, for the data sets in question, are used for calculating said basic group conformity measure. a) collecting previous-trip driving data sets, each of which is observed at a respective one of 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, which previous-trip driving data sets each comprises parameter values for at least a certain predetermined set of qualified driving data parameters in turn comprising the said basic parameter set, which set of qualified driving data parameters comprises instantaneous vehicle energy consumption, and which parameter values 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; b) mapping each of said current-trip driving data sets to a respective basic historic group of said previous-trip driving data sets using a basic group conformity measure between a current-trip driving data set and a basic historic group of said type, which basic group conformity measure is a measure of how closely the data set in question conforms to the basic historic group in question; and c) calculating an energy consumption-based trip performance parameter value for the current trip based upon a respective energy consumption-based group performance parameter value for each mapped basic historic group; wherein