Forza 4 Ultimate Challenge Ep. 14 Mercedes SLS AMG vs. Porsche 959 Hey guys what is up! This challenge was submitted by F1R3M0U53 saying to race the Mercedes SLS AMG against the Porsche 959 on Fujimi Kiado Reverse Track. The reason for the long track is for me to talk about my favorite car, the Mercedes SLS AMG! I hope you guys enjoy!