Abstract: A direct injection Diesel engine for motor-vehicles, with small displacement, is described, which comprises a number of cylinders in line each provided with two intake valves and two exhaust valves driven by two cam-shafts arranged in the cylinder head, by means of rocker arms. The arrangement of the intake apertures (2, 3) and the exhaust apertures (4, 5) is such that the injector device can be housed centrally therebetween and the pre-heating glow-plug can be housed on one side, between one intake aperture and one exhaust aperture, while the overall dimensions of the engine are greatly reduced and intake and exhaust conduits (6, 7, 8) are formed which ensure optimum performance of the engine and a low fuel consumption.