Blood is the best way to go. Just collect your gf's, mom's, sisters's, female friend's used tampons and pads and slowly smudge it on the seat and let dry. Repeat to achieve desired results. Its the cheapest method and best if the blood is somewhat fresh. Don't forget to thank us and show pics when it's done.
E89 Z4-35i DCT --- E36-Z3 M-Roadster --- E82-1M