How can I improve fuel efficiency in my Volkswagen Tiguan?

I recently purchased a Volkswagen Tiguan and I've noticed that it's not getting as good gas mileage as I expected. What are some tips and techniques I can use to improve its fuel efficiency?

Regularly maintaining your car with tune-ups and oil changes can improve its fuel efficiency.

Avoid unnecessary idling and aggressive driving to save fuel.

Consider investing in a fuel additive to improve your car's gas mileage.

Reduce the weight of your car by removing unnecessary items in the trunk to improve fuel efficiency.