What is the most efficient way to improve fuel efficiency in my Audi A1?

I have a 2018 Audi A1 and I am looking for ways to increase my fuel efficiency. What are some specific tactics I can use to save on gas for my Audi A1?

Utilize the car's built-in start-stop system, which turns off the engine when the car comes to a complete stop. This can greatly reduce fuel consumption in city driving.

Consider installing a performance chip or reprogramming your car's engine control unit (ECU). This can optimize fuel efficiency and potentially increase horsepower as well.

Regularly check and replace your air filter. A clogged air filter can decrease fuel efficiency by up to 10%.