i have been using this company called chemical guy for all my car care need ...... there products of off the hook there Fabric Carpet & Upholstery Shampoo is dope
I used tuff stuff on my wife's Mazda. It worked great and believe me with 4 kids and 2 dogs that ride in that car, they were bad. Tuff stuff took the stains right out though, pretty cheap also, I found it at dollar general for about 3 bucks a can.
It can definitely be a pain. I have a Maxi Cosi Tobi which you can buy summer covers for. These are a terry fabric which fits over the original cover but can be whipped off for cleaning easily.