Don’t be a tortoise. It’s obviously inefficient to make a “jackrabbit” start from a full stop. But because fuel economy is poorer in lower gears, “nursing your speed up to the limit too slowly also lowers mpg.” Be moderately bold: Taking 15 seconds to reach 50 mph uses less fuel than taking 30.
Don’t coast in neutral. Many fuel-conscious drivers choose to coast down hills in neutral. “This is a bad idea.” Not only is the tactic dangerous, it often wastes fuel. A fuel-injected engine consumes no gas at all when the vehicle is in gear, the accelerator is released, and the tires are rolling. If the engine is in neutral, it’s costing about two cents a minute.
Don’t turn on the air. Keep the air conditioning off when you’re just driving in town. It’s not until a car tops 55 mph that open windows create enough aerodynamic drag to offset the energy that the AC uses.
Source: Popular Mechanics