On a back-to-back test drive of both, the S4 I drove seemed to have MUCH heavier steering than the A4.

Is it really heavier, or was I just imagining things?

My gf has an B6 A4 that I drive often since we live together and HOLLY BEJESUS the steering on that car is so fvcking heavy that it's totally un-enjoyable to drive after driving my S4.

giving you the impression its "heavier".