I'm not going to bother with a capsule. I managed with DD in a reversible car seat and I'll just do the same again this time round.
Having said that, I know heaps of people who swear by their capsules, so I suppose it really is down to individual choice.
For me, I think those first couple of months are tricky with sleeps anyway, as they seem to always be asleep! I think if bubs falls asleep in the car, we'll just go inside, have another feed and hope she pops back off again, LOL. Perhaps I'm being fanciful