S3 fuel consumption vs A3 2.0T

[birdseed]

Hi all,
Apologies if this has been asked before but i couldnt find any references using the search function.

weve got an RS4 as the main car and are looking at either an A3 2.0T or a S3 as a more economical run around.

Ive had a 2.0T as a courtesy car before and got 40mpg on my commute to work.

Id be curious how different the S3 would be?

Thanks in advance