If you are looking for a carrier that is a back-pack, tote, messengar stlye but ALSO can be a safety seat in a car, Celltei is who you go to!
I have the Active Backpak-o-pet and it work wonders for our 2 yorkie pups! They are safe and comfy...
We even leave the top open so they can see out becauase there is a "leash" you can hook them to inside of the carrier that prevents them from jumping out!
Celltei thinks of it all... :-) Check 'em out...