If you do have to drive, minimize the amount of time you sit in idle. Hereâ€™s a pretty easy general rule of thumb to remember: if youâ€™re carâ€™s running and youâ€™re not moving, your gas mileage has dropped to zero mpg. I know for many of this, this is probably easier said than done, especially considering itâ€™s pretty tough to avoid the daily rush hour traffic. However, if you find yourself stuck at a stoplight or know that itâ€™s going to be a minute or two before you get moving again, turn off your car (assuming itâ€™s safe to do so). Essentially, it takes about ten seconds worth of idling to use as much gasoline as it would to restart your car; this means if youâ€™re going to be sitting at a stoplight for a minute or two, itâ€™s best to shut the car off and save gasoline.