Why is my Volkswagen Passat's fuel efficiency dropping?

I've noticed that my Passat's gas mileage has been significantly worse lately. I've been using the same driving habits and have kept up with regular maintenance. What could be causing this decrease in fuel efficiency?

It's possible that your tires may be improperly inflated or worn down. This can greatly affect your fuel economy. Make sure to check them regularly and replace them if necessary.

Have you recently changed your driving route or added any new accessories to your car? These could also impact your fuel efficiency. Consider removing any unnecessary items and trying a different route.

It's also important to make sure your air filter is clean and your engine is properly tuned. This can greatly affect your gas mileage. Consider getting a tune-up if needed.