Audi A4 and S4 leather seats offer a combination of luxury, performance, and customization, with the S4 model featuring sportier, more supportive bolsters. Base A4 models often come with heated, real leather seats, while the S4 can be equipped with optional front sport seats with electric adjustments, and premium materials like fine Nappa leather can be chosen for a personalized touch. Options include various colors, Nappa leather with diamond stitching, and customizable Audi exclusive finishes.