Re: Seat Covers?
I was thinking about making this exact thing for the same reasons. Coming back from the gym, I don't want gym funk all over my nice seats. I planned on using a waterproof, breathable softshell fabric with a deep "pocket" at the top that would go over the headrest (that way they wont slip down). Easy on, easy off means you can wash it whenever you want without any hassle.
If there's interest I'll start production lol