Gas prices always seem to be rising, so making smart decisions about your car's maintenance can help you keep it as fuel efficient as possible. One way to save gas is to inspect your spark plugs. Most cars have four, six or eight plugs, which ignite your car and help it run. Since each plug can "spark" as many as 3 million times for every 1,000 miles, they erode quickly and should be replaced regularly. Dirty or old spark plugs can cause misfirings, which waste fuel. Ask your mechanic to inspect your spark plugs the next time you get an oil change.