they are a no-no.<br>
You may use the spongy drawer liner stuff, or 1 very thin layer, like a receiving blanket or thin towel, if you absolutely must, but it's best not to put anything between the seat and the carseat. There are some techs who disagree, and say the spongy stuff actually helpss the carseat stay in place, because it's sort of grabby, but that is opinion. None of the plastic pieces or anything like that should ever be used.
We're getting a van in Nov., it will have leather (I hate leather, but dh is a pill and insists....<img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/irked.gif" style="border:0px solid;" title="irked">: ), and my bf was telling me how we "have to" get those seat protector thingies or else the leather will be "ruined." Now, I really don't care, personally. <img alt="" class="inlineimg" src="/img/vbsmilies/smilies/duck.gif" style="border:0px solid;" title="Duck">: It's a van that's going to be used with kids. I expect it to get messy. <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/lol.gif" style="border:0px solid;" title="lol"><br><br>
So if I decide I want to do something, I'll put that foamy crap down. Otherwise, meh, I don't care. <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/orngtongue.gif" style="border:0px solid;" title="Stick Out Tongue"> I'd rather have safe kids than intact leather.
Your leather will be fine. Just remember to treat it every so often with a leather conditioner, which should be done regardless of whether or not your car seats are installed. The great thing about leather seats is that spills and dirt just brush right off - they really are ideal for kids. lol<br><br>
But you're right, the seat protectors are not safe. They give the illusion of a secure installation, and invariably when they're used the seat slips around on the leather.