Bada Bing

Is it just Audi changing their rating to make the car look more efficient or did they actually tweak something to make it more fuel efficient? FWIW, I do show as high as 31 mpg on the trip computer for pure freeway driving, but my city driving mileage doesn't come close to 20 mpg. I wasn't getting much better with my previous GTI for the same city driving.

A4Audi4Fun

https://dieselnet.com/standards/us/fe_ghg.php#my2023

US Federal Government is continually modifying the test criteria so I suspect the car manufacturers tweak their ECU's to give them the best results needed for compliance.

Six-Pack

My guess; software.

TJay74

I always say the same thing to people, until you hand calculate your gas mileage you will never know the true rating. The computer is only a estimation of mileage based on the fuel injection data.

RickNY

Yup.

AA!

It's an S4, last thing I think about is the gas mileage.

92100CSQ

Bingo!

SMac770

It wasn't new to MY23. Audi seems to rate the S4 sedan, S5 coupe, and S5 sportback all the same.

MY18 - 21/30-24
MY19 - 21/30-24
MY20 - 20/27-23
MY21 - 20/28-23
MY22 - 21/30-24
MY23 - 21/30-24

MY20 was the facelift. Maybe the bumper changes weren't that aerodynamic and they had to hack the software to bring the results back to expectation. We'll never know.