How to improve fuel efficiency of Ford Transit Custom?

I recently purchased a Ford Transit Custom and I'm disappointed with its fuel efficiency. What are some tips and tricks for improving it? I'm looking for both practical and technical advice that I can apply to my van.

One way to improve the fuel efficiency of your Ford Transit Custom is to keep a consistent speed while driving. Avoid constantly accelerating and decelerating as it can waste fuel.

Make sure to keep your tires properly inflated. Under-inflated tires can increase fuel consumption.

Consider using a fuel additive to clean your engine and improve performance. This can also help with fuel efficiency.