I had a German Shepherd when I owned a Supra Turbo w leather seats. I bought a "sacrificial blanket" from salvation army for $5 and put that over the seats when he was in the car. Kept all the mud & dirt from park walks from getting on the car. Simple , cheap and effective.
I use to use it under my kids car seat but now I put it down if I'm going to put my dog on the front seat in the Miata (I can turn off the airbag on that side) and it seem to work well. What I use to do with our lab is put one of my t-shirts on her too. That kept the hair that flys around to a minimum. silly but it works and my lab is so mello she could care less...
2016 BRZ, 2010 Leg 3.6 R, 2013 OB, 2001 Forester S and 1999 Miata
Bought one of those bench seat hammock thingies after my dog sliced a clean 3" cut into my leather backseat the other day. In retrospect I should've probably chosen the quilted version, but I settled for the cheap one (well, not really that cheap either).