Why is the Audi A1 turbocharged engine more efficient than the non-turbo?

I am curious about what makes the turbocharged engine in the Audi A1 so much more efficient in terms of fuel consumption compared to the non-turbo version. Is it due to the forced induction or something else?

The main reason for the increased fuel efficiency in a turbocharged engine is due to the forced induction, which compresses the air and fuel mixture resulting in more power and less fuel consumption. However, another contributing factor is the smaller displacement of the engine, as smaller engines tend to be more efficient.