Method for determining the ignition advance as a function of the torque of a controlled-ignition internal-combustion engine by modelling, including, for a set of parameters: - A step in which the value of the advance is increased incrementally between an optimum advance value (AAopti) for which the torque is equal to the optimum torque (Copti) and a maximum advance value (AAmax) for which the torque produced by the engine is minimal, and the advance value is plotted, - A step in which the value of the torque produced by the engine is recorded for each advance value from the preceding step; - A step in which all of the pairs of advance and torque values corresponding to the various adjustment increments are recorded, - A step in which the aforementioned pairs of values are used to determine a parabolic relationship between the torque and the advance using an equation of the type: C/Copti = 1 − k * AA-AAopti 2 in which equation k is a positive constant, characterized in that it also includes at least: - A step of recording an advance threshold value (AAlin) for the advance which produces a torque threshold value (Clin), above which the recorded value of the torque produced by the advance is greater than the value calculated by the equation corresponding to said parabolic relationship, and a subset of pairs of advance/torque values for which the advance is greater than said advance threshold (AAlin) is used to determine a linear relationship between the torque and the advance, using an equation of the type: C/Copti = K * AA 0 − AAopti − AA-AAopti in which equation K is a positive constant and AA 0 is the advance for zero torque, - A step in which: - the preceding equations are inverted, determining the advance as a function of the torque using equations of the type: AA = AAopti + a * 1 − C/Copti 1 / 2, for torque values between said torque threshold (Clin) and the optimum torque (Copti) AA = AAopti − b * C/Copti + c, for torque values between zero and said torque threshold (Clin), in which the parameters a, b and c are positive constants; and - said parameters are saved in a memory of a processor of the engine, and a calculation block of the processor of the engine that is able to adjust the ignition advance as a function of the torque is used to program a sequence of instructions for said adjustment, including at least a step for comparing the torque with the torque threshold (Clin) and a step for calculating the advance according to equation 3 or according to equation 4 according to the result of said comparison. - A step in which the value of the advance is increased incrementally between an optimum advance value (AAopti) for which the torque is equal to the optimum torque (Copti) and a maximum advance value (AAmax) for which the torque produced by the engine is minimal, and the advance value is plotted, - A step in which the value of the torque produced by the engine is recorded for each advance value from the preceding step; - A step in which all of the pairs of advance and torque values corresponding to the various adjustment increments are recorded, - A step in which the aforementioned pairs of values are used to determine a parabolic relationship between the torque and the advance using an equation of the type: C/Copti = 1 − k * AA-AAopti 2 in which equation k is a positive constant, characterized in that it also includes at least: - A step of recording an advance threshold value (AAlin) for the advance which produces a torque threshold value (Clin), above which the recorded value of the torque produced by the advance is greater than the value calculated by the equation corresponding to said parabolic relationship, and a subset of pairs of advance/torque values for which the advance is greater than said advance threshold (AAlin) is used to determine a linear relationship between the torque and the advance, using an equation of the type: C/Copti = K * AA 0 − AAopti − AA-AAopti in which equation K is a positive constant and AA 0 is the advance for zero torque, - A step in which: - the preceding equations are inverted, determining the advance as a function of the torque using equations of the type: AA = AAopti + a * 1 − C/Copti 1 / 2, for torque values between said torque threshold (Clin) and the optimum torque (Copti) AA = AAopti − b * C/Copti + c, for torque values between zero and said torque threshold (Clin), in which the parameters a, b and c are positive constants; and - the preceding equations are inverted, determining the advance as a function of the torque using equations of the type: AA = AAopti + a * 1 − C/Copti 1 / 2, for torque values between said torque threshold (Clin) and the optimum torque (Copti) AA = AAopti − b * C/Copti + c, for torque values between zero and said torque threshold (Clin), in which the parameters a, b and c are positive constants; and - said parameters are saved in a memory of a processor of the engine, and a calculation block of the processor of the engine that is able to adjust the ignition advance as a function of the torque is used to program a sequence of instructions for said adjustment, including at least a step for comparing the torque with the torque threshold (Clin) and a step for calculating the advance according to equation 3 or according to equation 4 according to the result of said comparison.