I got these ideas from a website in Britain. It was published as a guideline for the UK but it applies just as well in the US. I know some of these have been mentioned on this site before but they bear repeating. Take a look and see if there is something you can use:
1. Only use your car if it’s necessary. If the destination is close by, walk or bike it.
2. Keep your car well maintained. A poorly tuned engine can up fuel consumption by a massive 50 per cent.
3. Plan your journey. According to the RAC, British drivers waste the equivalent of 267 Olympic swimming pools of fuel going the wrong way.
4. Remove unused roof racks. Due to the extra drag, they increase fuel consumption by up to two per cent on the motorway.
5. Fill up early morning or late at night when it’s cooler because fuel is denser then and you’ll get more into the tank. The difference may be pennies, but it all helps.
6. Check tyres are properly inflated. Underinflated tyres can reduce fuel efficiency by up to three per cent.
7. Don’t use air conditioning. It increases fuel consumption by eight per cent.
8. Drive at 56mph. This is the most fuel-efficient speed. Slowing down to 56mph from 70mph will cut fuel consumption by 20 per cent.
9. Don’t accelerate quickly then brake hard at the next traffic lights. By raising speed gradually and paying attention to traffic conditions, you’ll increase fuel efficiency by up to 20 per cent.
10. The lighter your car, the less effort is needed to accelerate. So clear junk from the boot and avoid carrying unnecessary weight. Fuel efficiency can rise by up to two per cent.