Automotive speed reducer

The utility model relates to an automotive speed reducer which comprises the following components: a differential, an input shaft, an output shaft, a housing and a clutch housing. The input shaft passes through the housing and is connected with a clutch in the clutch housing through an input spline gear. The clutch is connected with an engine. The input shaft is provided with the following gears respectively from top to bottom: an input fifth gear, an input fourth gear, an input third gear, an input second gear, an input reverse gear and an input first gear. A third/fourth synchronizer is provided between the input third gear and the input fourth gear. The output shaft is provided with an output shaft output gear. One end of the output shaft is connected with the clutch housing. The automotive speed reducer is beneficial in that: an integrated design which comprises speed change, differential and speed reduction is adopted; a compact structure is adopted; an integrated design for gear selection and gear chang