Traveling by car or by any other means of transportation often represents the journey through life.
Therefore, if you dream of using an accelerator to increase speed it can mean that you wish for things to proceed more quickly in your life.
If someone in your dream is trying to encourage you to use the accelerator it could be a suggestion for you to not waste time in achieving your goals, or if the feeling is unpleasant in your dream it could be that you are feeling pressured into moving too quickly.