Abstract
A fundamental feature of the automobiles engines is the great variety of their working regimes. The full load (i.e. wide open throttle) situation is a very seldom one since the engine´s operation occurs mainly at part loads corresponding to the urban traffic. Although, the maximum thermal efficiency of the actual spark ignition engine is of about 35%, in case of the vehicle´s urban use it doesn´t exceed 10 - 15 %. Indeed, the latter case is mainly encountered (80 - 90 % of the total vehicle´s operational life), having thus an overwhelming contribution to the engine´s fuel consumption.
Keywords: fuel economy, load control, variable valve timing and lift, throttle-less