The car seat/carrycot thing is confusing, isn't it. I got a carrycot part with my travel system which, in theory, could be used in the car. However, I'd just read a Which? report describing in-car carry cots as deathtraps, which kind of put me off using it. The one I had (Janè), just had a wide strap thing to hold the baby in place round the waist, and I really think that's insufficient, in an accident their head would go all over the place.
Best to stick to rear facing seats, but now they're saying there's issues for those too, as far as the baby's position, breathing etc. goes. I think the only thing you can really do about that is try and avoid long journeys for the first 3 months.
Speaking of car safety, one purchase I would recommend you all consider is one of these , I actually had a car accident (idiot drove right into us) last time I was pg, at around 6 1/2 months. Everything turned out ok, but I got bruising on my bump from the seat belt, and it was quite stressful at the time. Anyway, wish I'd had one of these bump belts, it could've saved me a bit of worry.