The system of the invention includes sensors (11, 12, 13) for measuring physical values useful for driving assistance, a path correction electronic calculator (20) including a Hill Assist (HA) module for hill start assistance and a Hill Descent Control module for limiting the downhill speed, and actuators (31 to 35) controlled by said calculator for acting on the different driving parameters. The calculator further includes a Hill Assist Descent Control (HADC) for driveability control assistance in slopes, that enables or disables the Hill Assist (HA) and Hill Descent Control (HDC) modules based on specific control rules for managing intermediate life situations between the situations managed by the Hill Assist (HA) module and those managed by the Hill Descent Control (HDC) module. The invention also relates to automobiles and to automobile driving assistance systems.