When should I change the spark plugs in my Ford Fiesta?

I've been noticing some performance issues with my Fiesta and I'm wondering if it's time to change the spark plugs. How often should I do this and what signs should I look for?

It is recommended to change the spark plugs every 30,000 miles or 2 years, whichever comes first.

Signs that your spark plugs need to be replaced include a decrease in fuel efficiency, difficulty starting the engine, and a rough idle.

I would also recommend checking your owner's manual for specific guidelines for your Fiesta model.