Why is my Nissan X-Trail's fuel economy decreasing?

I've noticed that my Nissan X-Trail seems to be using more gas than it used to. What could be causing this and how can I improve my fuel efficiency?

Have you checked your tire pressure? Underinflated tires can greatly impact fuel efficiency. Make sure to keep your tires properly inflated.

Another possible cause could be a clogged air filter. Make sure to regularly check and replace your air filter to improve your fuel economy.