Leatherique is great but very expensive. If the steering wheel is the only leather you will ever clean, don't even consider buying it. If you have leather upholstery, or furniture in your house or even leather clothing, it's worth buying.
Magic Eraser is too rough for leather, IMO. My mother in law took the clear coat off of her Accord in several spots using a Magic Eraser. They're much more abrasive than they look or feel to the touch.
Simple Green will eat the leather up. It'll clean it, but in a few months, the leather cover of the steering wheel will be peeling off.
So, if you don't have enough leather to warrant the expense of Leatherique, I second the notion of using Meguiar's leather cleaner. Buy the yellow liquid that comes in the spray bottle or the foaming stuff, which I have found works surprisingly well. Apply it liberally, then use a SOFT (not stiff) brush to scrub any areas that don't come clean with a terry or cotton cloth that you turn often. I wouldn't go any stiffer than a soft toothbrush.
Once it's clean, condition it with the milky Meguiar's leather conditioner. Steering wheels take alot of abuse, both from your hands and the sun.
FTR, I don't think Meguiar's leather cleaner is special. Probably any name-brand leather cleaner will do--Mother's, California Gold, Adams, Griot's, etc. OTOH, Leatherique IS special. If you buy it, you'll see.
HTH, James.
