The development of quiet electric motorizations has led to a radical change in the acoustic feedback that the driver perceives in the passenger compartment. Although one might think that this noiselessness might improve the comfort, internal combustion engine noise is a major source of information for the driver. Even ,'combination of visual, vestibular and acoustic information. To evaluate the influence of sound on motion perception, two experiments were conducted in a driving simulator. Participants were asked to accelerate or decelerate to a given target speed in the absence of a speedometer with three sound conditions: internal combustion engine, electric motorization or no sound. The results confirmed that acoustic feedback can influence motion perception, and showed that the engine noise plays a leading role in speed estimation. Without engine noise and even more without any sound, it was more difficult for the participants to precisely estimate the target speed and to keep it constant. Consequently, drivers might be forced to pay more attention to speed regulation in quiet vehicles, which might lead to an increase in their cognitive load and consequently affect their driving performance.