these things aren't that great for your (4!) cats. Remote start/idling is the slowest way to warm your car up, and because of that, your cats warm up as slow as possible. Cold cats not only don't work effectively, but it greatly reduces the life of your cats as well. And, for the record, they aren't cheap to replace.
It might be worth it in extreme climates but I'd shy away in most places.

 

cats i hate them! i like dogs more! and i wanna remove them anyway!

 

Oh really? Says who?