How do I improve the fuel efficiency in my Vauxhall Vivaro?

I've been noticing a decrease in fuel efficiency in my Vauxhall Vivaro. What are some steps I can take to improve fuel efficiency and save money on gas?

Regularly check your tire pressure and keep them properly inflated. This can greatly improve fuel efficiency.

Avoid aggressive driving habits such as quick acceleration and braking, as this can use up more fuel.

Consider using a more lightweight oil for your engine, as it can reduce drag and improve fuel efficiency.