Yeah, not really. The only way to bulletproof your car from kids is to just watch what your kids bring into it. Set rules that even the adults follow. No open containers and nothing but dry foods, if anything, gets brought into the car. Shoes get stomped out before you get in the vehicle just like your house. And even with the best intentions you can bet that someone is going to rip open a bag of gum drops and spray sugar everywhere that you'll have to deal with, so Scotch Guard really isn't going to save you from much. It will help save you if you catch the spill right after it happens, but it doesn't last very long and you have to keep reapplying it.
It is sort of like car insurance. I've been paying it for twenty years and never needed it, but you know the one time I miss a payment is going to be the time I rear end someone. The one time you skip applying it will be when they lick the top of their strawberry ice cream cone right down the middle of your seats. It is better to just get into good habits about what goes into your car.
But the car seat mats serve more purpose than just catching stains. The first car seat you have in there is going to be buckled down for probably at least a year and a half or two years if not more. Then they'll need something larger than the backwards facing seat and you'll be strapping down a bigger chair for the next three or four years. Kids have to be in car seats till they are somewhere between 8 and 12 years old and the seatbelt fits them correctly. So whether it is four point harness seats or just booster seats, there is going to be something strapped down back there for a very long time. You can always tell the cars that have had car seats in them long term because there are wear marks in the upholstery or leather. Covers like the one I showed you will save your car from damage from the car seat as well as catch stain causing crud from ruining them further. In my experience it is that first car seat that does the most damage because it is the one that is buckled down the hardest. So definitely at least put a towel between the platform and the seat before you lock it down.
Oh, one other idea someone gave me was to use bathroom runners. Those bathroom mats have grippy bottoms on them so they don't slide off the seats. Kind of clever I thought. They would probably do the trick at protecting the seat from car seat damage too. Just a thought.