The nappa is a much softer leather. I really love this type of leather. The Nevada is indeed quite tough in comparison and when I first got my car found that they were actually quite uncomfortable. However after time the leather does give and is then more comfortable but still no where near the nappa. Great for longevity though. The merino is somewhere in between in terms of it's suppleness. The merino is harder wearing than the nappa.

So in terms of softness nappa>merino>Nevada
And the reverse is true on how hard wearing they are. The nappa needs to be well looked after.

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2009 135i M Sport Convertible
2008 X5 3.0si
2003 E46 318Ti M Sport Compact - donated to parents
2003 116i Hatchback - donated to brother
2002 316Ti - Sold
2000 318ci M Sport - Sold
1998 318i Sedan - Sold