Nomad Plus

The Maxi-Cosi Nomad Plus is a folding car seat that you can carry like a small suitcase when not using. A friend bought it to travel around the States and it’s still in great condition after lots of flights as the seat part is covered when folded. Fits under a pushchair, so I have borrowed for train journeys when being picked up in a car at the other end - it’s great and quite light. But honestly when I have flown myself I’ve always rented one with the car and they’ve always been cleaner than ours!

We love this car seat! https://www.maxi-cosi.ie/car-seats/nomad-plus We travel a lot with our 2.5 year old, as well as living in a city without a car, and this car seat has been amazing for us! Only downside is that there is no rear facing option.

When we went to Switzerland last summer we bought this: https://babyplus.store/product/maxi-cosi-nomad-i-size-car-seat/ Now we take it on every trip. My daughter is 3 so it will last her a bit longer. It’s awesome and installs relatively easily.

I live in Singapore. We use this https://www.maxi-cosi.com/international/car-seats/nomad-plus It’s pretty easy to install in Grabs/Ubers.

I live in a big city with lots of public transport. I try to use it exclusively, but I can’t always. Don’t own a car and similar to you have this dilemma. I use this seat if I have to. I’m not thrilled about it. https://www.maxi-cosi.com/international/car-seats/nomad-plus

I live in Singapore. Many of our friends got the Doona Car seat and Stoller which folds up easily from a stroller into a car seat and then put into a Grab. We chose the Nuna car seat which is light and can latch into most Grabs easily. It can attach to our stroller. These are infant car seats which are easier to install. Once they get too big for them you either can use Grab Kids which has a car seat in it or find a different model. We chose to use the Maxi Cosi Nomad which is a more portable toddler car seat.

There are a few brands of foldable car seats, Maxi Cosi has one that's good from 15mo. They are expensive but honestly the price of getting the crappy one from the car rental place is about the same. Once you get too booster seat age, then the MiFold and the Boostapaks are good options

Personally I wouldn’t trust taxi or hire companies to provide a car seat which was an appropriate stage, a seat I felt safe using and one I trusted had never been dropped or in an accident. Your son is at the awkward stage been infant carrier (unless he’s very small) and HBB, both of which are more portable than the toddler seats. If he still rear faces, the cheapest option for travel seat I see recommended is the Graco Slimfit R129 but it’s still bulky. On the smaller but pricier end there’s the TinySeats Two (which folds) or Nachfolger HyFive World (which is inflatable). If he’s forward facing the Maxi Cosi Nomad could work. [Just don’t get anything like this](https://www.which.co.uk/news/article/why-are-ebay-and-amazon-still-selling-killer-car-seats-a4kjj8v3Jxp6) from Amazon or Temu or TikTok Shop. The link has a crash test included and they aren’t crash tested so just fall apart. You’d be better strapping him into the car seatbelt than one of those.

You could get a folding high back booster for the 3 year old (not ideal but as it's only for a transfer your risk appetite might be ok with it) like the Be Cool Foldy or the MaxiCosi Nomad. And then depending on the weight / height of the 18m old do they still fit in an infant carrier? If so you could buy a cheap one like the Joie Juva. Or Joie Steadi to travel with.