<p>Hi</p><p>Are these sentences natural? Any suggestions are welcome. </p><ol><li>The car soon <b>speeded up/sped up.</b></li><li>Can you <b>speed up</b> a bit please? I may miss my flight. (<i>requesting the driver of the car</i>)</li><li>You must<u><b> speed up</b></u> or you won't be able to meet the deadline.</li></ol><p>Thanks,</p><p>Tom</p>