There is hardly much difference between the new Ausi S3 and the old 2021 RS3: sure, the grilles and trim details are different, but the outlines match almost exactly, as do the curb weights, and the gearbox used is the same in both cases.
The old-gen RS3 has a small power advantage thanks to its 2.5-liter turbocharged five-cylinder delivering 340 PS (335 hp / 250 kW) to the wheels. That said, the S3 gets a comparable 310 PS (306 hp / 228 kW) from its 2.0-liter turbo four-pot and even has more torque at that.
So, which one do you think will turn out to be the fastest on the drag strip? Let’s put it like this: both have their fair chance at winning, and the outcome will boil down to who has the fastest reaction at the start.