We use SnS meridian for our newborn (we would use our SnS unity capsule but too hard)
but go on either choice or RACV (not sure what its called in perth sorry) and it sould have car seat ratings

my fav brand is SnS but other cheaper brands to have just as high safety rating (not sure on other seats rating as high as SnS Meridian)
your local baby stores should also have pamplets on car seats rating

sorry i couldnt be more helpful