An automatic method for determining at least one so-called global inclination of a motor vehicle when driving along a trajectory on a road, said global inclination ( α) illustrating the angle between a reference longitudinal axis of the chassis of the motor vehicle and a reference longitudinal axis of the road on which the wheels of the axle of the motor vehicle rest, said method comprising: - a measuring step performed by means of at least two accelerometers (A1, A2) arranged on the chassis, the two accelerometers (A1, A2) being configured to measure over time, respectively, a so-called longitudinal acceleration and a so-called vertical acceleration of the motor vehicle, the measuring step consisting of measuring a plurality of pairs of successive measurements, each pair of measurements comprising a measured longitudinal acceleration and a measured vertical acceleration; - a calculating step performed by a calculating unit and consisting of calculating the global inclination ( α) of the vehicle exclusively by means of pairs of measurements measured in the measuring step, said calculating step taking into account that the vertical acceleration and the longitudinal acceleration are linked by an affine function of which a coefficient of proportionality depends on a point-inclination for a constant slope of the road, wherein the calculating step comprises a series of successive substeps, performed in an iterative manner and comprising: • a first calculating substep consisting of performing a linear regression, by means of a plurality of pairs of measurements, in order to determine a coefficient of proportionality; • a second calculating substep consisting of estimating a point-inclination, from said coefficient of proportionality determined in the first calculating substep; characterised in that the calculating step further comprises: • a third calculating substep consisting of calculating an estimation quality value (q) of the point-inclination estimated in the second calculating substep; and • a fourth calculating substep consisting of determining, with each iteration, a current global inclination, from the set of estimation quality values and point-inclinations calculated and estimated in preceding iterations, the current global inclination calculated in the last iteration representing said global inclination ( α). - a measuring step performed by means of at least two accelerometers (A1, A2) arranged on the chassis, the two accelerometers (A1, A2) being configured to measure over time, respectively, a so-called longitudinal acceleration and a so-called vertical acceleration of the motor vehicle, the measuring step consisting of measuring a plurality of pairs of successive measurements, each pair of measurements comprising a measured longitudinal acceleration and a measured vertical acceleration; - a calculating step performed by a calculating unit and consisting of calculating the global inclination ( α) of the vehicle exclusively by means of pairs of measurements measured in the measuring step, said calculating step taking into account that the vertical acceleration and the longitudinal acceleration are linked by an affine function of which a coefficient of proportionality depends on a point-inclination for a constant slope of the road, wherein the calculating step comprises a series of successive substeps, performed in an iterative manner and comprising: • a first calculating substep consisting of performing a linear regression, by means of a plurality of pairs of measurements, in order to determine a coefficient of proportionality; • a second calculating substep consisting of estimating a point-inclination, from said coefficient of proportionality determined in the first calculating substep; characterised in that the calculating step further comprises: • a third calculating substep consisting of calculating an estimation quality value (q) of the point-inclination estimated in the second calculating substep; and • a fourth calculating substep consisting of determining, with each iteration, a current global inclination, from the set of estimation quality values and point-inclinations calculated and estimated in preceding iterations, the current global inclination calculated in the last iteration representing said global inclination ( α). • a first calculating substep consisting of performing a linear regression, by means of a plurality of pairs of measurements, in order to determine a coefficient of proportionality; • a second calculating substep consisting of estimating a point-inclination, from said coefficient of proportionality determined in the first calculating substep; • a third calculating substep consisting of calculating an estimation quality value (q) of the point-inclination estimated in the second calculating substep; and • a fourth calculating substep consisting of determining, with each iteration, a current global inclination, from the set of estimation quality values and point-inclinations calculated and estimated in preceding iterations, the current global inclination calculated in the last iteration representing said global inclination ( α).