The apparatus and method of the invention vary the sensitivity slope of the FNR control lever of an agricultural windrower, such that speed commands outputted through a first range of movements of the FNR lever are slower and increase less rapidly than commands outputted through a second range of movements greater than the first range, the first range corresponding to movements in closer proximity to the neutral position of the FNR lever. The different show is achieved by using different slopes for transfer function signals for the first and the second ranges of positions of the FNR lever.