Characteristics of relief of the new engine are the block and the heads in aluminum, the distribution with overhead valves, the cast-iron cylinder bore directly cooled from the liquid and the camshaft chain hydraulic driver, pushed from the oil pressure. Many other details of the Aurelia show the desire of perfection at the base of his plan: for example the friction-gearbox-differential group placed at the rear for a better balanced distribution of the weights, the in-door rear brakes to reduce the suspended masses , the indipendent suspensions (two different models of rear suspension were employed, first with coil springs and oblique rods, then with leaf springs and De Dion layout).