Clek - Fllo Convertible Car Seat

If you want good three across seats, without flame retardants, Clek Fllo and Foonf both come in a couple of totally flame retardant free fabric options. I have Mammoth Fllos for my twins and they are great. They do extended rear facing until 40lbs (in Canada) or 50lbs (in USA) iirc, which is a really important safety feature - you don’t want to turn them around too early. If you want to only do two seats, the only seat I can think of that wouldn’t drive me nuts are the Britax clicktight seats - some of which are flame retardant free - but I don’t know if you could find one that would still do three across. The click tight seats are really fast to install securely, I had a Harness-to-Booster one for my oldest child when they outgrew the Clek Fllo but weren’t ready for a booster (95%ile kids are a car seat challenge) and I had no qualms uninstalling and reinstalling that seat whenever I needed to.

 I personally don't recommend starting with a convertible car seat just because in my experience they dont fit newborns/small babies well. Even my high percentile 4 month old felt too small and didn't have the neck control for the extend2fit when we tried to switch at 4 month and didn't fit well until closer to 6. If you do go that route the only one that would probably be okay is the cosco next from what I've read from CPST. Even though its convertible though it only works rear facing and baby will probably out grow it around 2 year old and you'll have to get a second seat. I think the Cleks convertible also fit newborns well, but they're very big back to front so I'm not sure it'll fit your car tbh.  We have a Kia Soul and got the chicco key fit 30. It worked pretty well and we used it a similar amount (or even less tbh) than you plan to. We ended getting a travel stroller that was compatible with it to leave in the car instead of our big stroller. Like everyone said the Graco and Clek Lling would work as well. I will say I think I wish I had gone with the Lling instead but it just seemed too expensive for a seat my son outgrew by 7 month. 

CPSTs don't recommend Nuna seats because for the same price you can get a Clek which is a much longer lasting seat. Or so I understand. We have the Fllo and it's great but I will add that the baby still does not love getting into her carseat. It's unfortunately just a thing

yes as the other person mentioned, Clek is the brand, the Fllo is a model name for their convertible carseat. The Foonf is their other convertible. (Liing is the infant seat which you should skip). We ordered ours directly from Clek! They have very high rear facing weight limits and they're built like tanks. We've had great customer service from them too. If it's in your budget and they are good fits for your vehicle I recommend checking them out.