We've just had our second.
We never bought a stand alone rear facing seat. We bought a pram with the interchangeable bits. We got the Concord Neo which comes with car seat, cradle thingy and a buggy type bit with one of those cosy toes covers. For babies first seat it's much easier to get one that you just clip onto a pram as trying to put a new born into a seat in a car isn't easy plus it's one less thing to buy/carry around with you.
All the kit we bought has lasted well and it has seen some serious abuse being pushed round a farm on a daily basis.
We didn't go for isofix as in the 2 years that we've had kids we've had 10 cars in the family and not all of them have had isofix. No worries with fitment in any car in terms of sports. That includes the seat being fitted in M sport seats and Audi buckets which are much narrower with larger bolsters than I've seen on any BMW.