When possible, try to combine your errands into longer, multipurpose trips instead of driving out for several shorter trips throughout the week.
You'll save time, gas, m... read full tip

When possible, try to combine your errands into longer, multipurpose trips instead of driving out for several shorter trips throughout the week.
You'll save time, gas, money, and wear and tear on your car by reducing the miles you drive. Additionally, your car will run more efficiently if trips are taken when the engine is warm, as opposed to taking multiple trips from a cold start.
If you combine five errands per week that you might normally break into five separate trips, you could end up driving 2000 miles less per year. In doing so, you could save almost 100 gallons of gasoline, and nearly $300!

If every household in America combined just two errand runs per week, the total savings would be nearly 2 billion gallons of gasoline-equivalent to the amount that would be conserved if the entire country gave their vehicles a rest for a whole work week.

FuelEconomy.gov
U.S. Department of Energy