The armrest surface is showing erosion back to tan-leather color from the blue - my '83 300SD with the identical color blue interior did exactly that after 250K miles, and 13 yrs. The right driver's seat-bolster is showing the same wear too.

It is also possible that exposed surfaces have been affected by sea-salt air in Pensacola. Not necessarily likely - but possible nonetheless.

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'06 E320 CDI
'17 Corvette Stingray Vert