So, I used my wife's Kia Sorrento this weekend and somehow managed to put a small (dime sized) tear in the 2nd row seat back that faces the cargo area. The seat back itself is black carpet material.

It really doesn't look that bad but it drives me nuts knowing it is there however a hew seat back is 400.00 and god knows how much to install so that is off the plate.

Anyone have any experience with auto carpet repair?

Go to an upholstery repair shop, usually they can fix things like this pretty reasonably

I just found and old guy that runs a little shop near me and am going to stop by!

There are specialists who cater to the used car industry that have techniques to handle this kind of thing. Sometimes, they are almost invisible, other times not, but generally very affordable. Call some of the larger used car retailers near you.

In my experience, upholstery shops can generally do a better job using more traditional techniques, but for a higher price.