This is my first venture with Sugru, so this may go well or not, but with a spirit of adventure and a camera in hand, I cautiously venture forth.
Step 1: Vinyl Armrest Repair
The interior of my van is gray, so I grabbed one packet of black and one of white. I started with the small lump of the white, thinking it would be easier to add bits of black until it was dark enough, rather than the other way around.
Lastly, I used a small pair of pliers to put a small detail line in the Sugru to match the existing form. There is texture on the arm that was not confident I could reproduce, so I stuck with just smoothing it out. I'm not perfectly happy with the color or texture, but certainly this repair is an overall improvement.