Originally Posted by Goldwing
Change your entry/exit habits as well. Left bolster wear is due to sliding in and out of the car. If you kind of plant your butt into the middle of the seat and swivel, it's less wear on the bolster. Otherwise, leather treatment will help but not undo the damage.
On our Jaguar XK, I used a shoe leather dye (in tan) from CVS with a watercolor brush and applied it to the driver's boulster scuffs. Shockingly, it looked good and was 95% unnoticeable. I was pretty proud and managed to avoid the jaw dropping recover price.