What is the best way to increase fuel efficiency in a Ford Transit Custom?

I recently purchased a Ford Transit Custom and have been trying to find ways to improve its fuel efficiency. I've heard about various methods like using premium fuel or adding performance chips, but I'm not sure which one is the most effective. Any advice on how to increase my car's fuel efficiency?

Using premium fuel may increase your car's fuel efficiency, but it's not a significant difference. Instead, focus on regular maintenance, such as keeping your tires properly inflated and changing your air filter regularly.

Adding a performance chip can improve your car's fuel efficiency, but it can also void your warranty. Before making any modifications, consult with a certified mechanic and consider the potential consequences.