3 in the back - which of these car seats are narrowest?

[oopsa]

We're trying to squeeze 3 car seats in the back of our car. We now need one more booster/with back style seat for 4 yrs/15kg plus.
Does anyone know of a really narrow one - we're currently thinking it might be Maxi Cosi Rodi (not sure which model), Britax Hi-liner and a Concord one (Lift Protect)? Any clues to which of these are slimmest - doubt we'll find a shop to compare them side by side! Or is there another slim one I should consider?
The thought of having to change cars is just too much...

Britax HiLiner is narrow - we fit it into the back of our Zafira along with 2 stage 1 seats. What car do you drive and what other seats do you have?

We have three car seats in the back - one mamas and papas stage one jobby and two britax eclipses - it is a squeeze but they fit.

I have the maxi cosi rodi in the back of my car with a graco baby carrier thingy 0+ either side of it for the twins.

very soon will be changing them into forward facing ones the the maxi will stay in the niddle (to stop twins fighting )

This one is quite narrow. It is great when the DCs fall asleep in the car as it has a special support thingy for the head.