Nice job. I have the same SL63 car, of similar age, so will need to do the same job. Someone in the motor trade recommended using 'Brisk VIF Auto' for this. It's a dry foam upholstery & fabric cleaner but as you say, any decent leather cleaning product should do the job.
I'm pretty sure that's the wrong product for the job, it;s gonna leave the wheel with residue. Try Sonax upholstery Alcantara cleaner it works great, also an old toothbrush works well to clean and fluff up the fibers
