When I got my 164e the leather was hard and cracked and even split in a couple of places. I didn't want to spend big bucks on a retrim so I invested $175 in a Leatherique restoration kit. This includes a conditioning oil,cleaner, dye, and crack filler.Enough to do all the seats. The kit recommends that you scrub the leather with paint thinners first and then apply the products in stages over about 4 days. It's actually the old surface coating that goes hard. As soon as you remove it, the leather is soft again. I took the seat covers off the seats and repaired the splits by gluing patches on the inside and filling the cracks on the outside with the crack filler. The filler is flexible and can be sanded down to the surface of the leather before you dye it. It was a lot of work but the result is unbelieveable.The leather is soft and supple and color is back to original. If your leather is not too torn up, this is the way to go. Much better than two grand for a retrim.