hi nelle- i dont have an answer to your question- but i am interested in the answer.... my DH also wants a capsule for the first few months (he waited till after i bought the convertable newborn -toddler car seat to tell me this!!) so we are contimplating hiring one now too- or thinking just buy one so we have it there for the next bub too...

I had never heard of it possibly being harmfull to their back... i spose part of me thinks.. whats the difference between a looong car trip and a bit of a sleep after a short drive??? I would think if it was un safe it would be unsafe while they are in the car too... hmmmm Also i thought people bought capsules for bubs to sleep in whether in the car or not anyway... does anyone else know any different?