anything that doesn’t resemble a portakabin?

Seat alhambra. Very very spacious, very very practical. You don’t see the outside when you’re sat in it.

It would be worth going to see one. We run one as pool car at work and I’m seriously considering getting one.

Smax had them. Expect most people carriers with separate style seats will do.

Choices are limited. We went down the caravelle route as we need to cart around two doddering pensioners and luggage too. Lovely but thirsty and hilariously badly made.

smax, shalhambraxy, espace, touran? Not sure a grande scenic can do it. Nothing “nice” can. Have you looked at a multimac (just don’t get involved in a side impact)?

I don’t think isofix is really the concern – astras and a3s have 3x isofix but you won’t fit 3 childseats across the back; likewise most carseats have a belted option too (group 2 and above its what actually holds the seat, the isofix just stops it rattling round when unbelted)

If you want to ask which cars can fit 3 seats across the back, it’s limited, large 4x4s and people carriers are about it

5lab is correct in what he wrote.

5lab is mostly correct – especially about the “why 3 isofix” thing.
Loads of threads on here about 3 seats across the back – have a search.

My mate has a 3 seat arrangement in a VW Golf Mk6.

I think most cars are possible.

something that we looked at, but discounted because of the ages of our kids were these high back booster seats from volvo, which are very slim & deisgned to fit 3-abreast:

linky

Very happy with our Alhambra over the past 3 years. Very robust, Three individual seats in the back and the two extra in the boot are adult size with more leg room than the rear 3 when in place.

Alternatively something a lot smaller like the standard sized Picasso or whatever it’s called now, has 3 individual iso fix seats, and thus shaped better than a normal rear bench.

We tried to get a car which didnt look like a portakabin with 3 kids seats accross the back years ago and it was next to impossible, you could cram them in but they wouldnt be sitting properly and the doors would usually hit them when closed. We ended up with a Touareg at the time until number 4 came along and bought a Sharan which has loads of room and the seats fit properly.

Mk1 SMax only has two. Middle seat doesn’t.

We’ve had my daughter’s seat in it though without problem using the seatbelt.