If you do have to drive, minimize the amount of time you sit in idle. Here’s a pretty easy general rule of thumb to remember: if you’re car’s running and you’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 it’s pretty tough to avoid the daily rush hour traffic. However, if you find yourself stuck at a stoplight or know that it’s going to be a minute or two before you get moving again, turn off your car (assuming it’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 you’re going to be sitting at a stoplight for a minute or two, it’s best to shut the car off and save gasoline.
>  The Top 10 Ways to Reduce Your Gasoline Consumption by Daily Fuel Economy Tip