WE haven't had our leather furnished cinquecento very long, but my motorhome has leather, and that old bus is 1999 vintage. I give all the leather (and there's lots of it)! a thorough cleaning with Mer leather clean and feed twice a year. So far, there is no sign of cracking or any other damage, and it still looks fresh. the colour is cream, so it would be prone to getting dirty. I use the same stuff on the leather on the Stressless chairs in the house, and they still look good too.
I'm pretty sure that any good brand leather clean and feed product will help.
I do try to make sure that I wash my hands before driving the cc too, which is possibly a little sad.