Narrow/smaller car seats

Not sure where to put this but figure here is a good spot. We will need to upgrade to a larger car once (well before) # 3 arrives. We are not in the best financial position to be able to just run out & get refinanced etc. We are working towards it though.
But I had a thought today that maybe a cheaper (make do) option if for some reason we can't manage to get a bigger car in time would be to get smaller baby seats. ATM we have a reversable "go safe" seat & also a reversable "mothers choice". Basically identical seats. Also a booster seat for Evan. I have on layby another booster seat for when Glenn is ready to move up from the baby seat to booster, so he will move to Evans booster & Evan will get the new one & baby will have baby seat. But I thought If I could get a smaller reversable seat then I may be able to fit all 3 in the back seat of the car we have. I doubt it but still worth looking into to see.
So my question is which is the most smallest/narrow car seat available?
We have a Hyundia Lantra at the moment I wouldn not fir a 3rd seat in the back, not even 1/2 of a 3rd seat so I do think it is a long shot but any ideas? I did see a seat in big W that looks alot narrower then the seats I have thats what made me think it was possible....

I have the Safe & Sound Compaq deluxe which was apparently the smallest/narrowest seat on the market when I bought it for DD 2.5yrs ago. We had a Daihatsu Charade & this seat only took up one seat, we could get 2 passengers in the back alongside the seat.
I love it has been great but not squishy iykwim!

I have the Go Safe compact and I always thought that was the smallest/most compact one in the market but maybe Skyelar is right about the Safe & Sound one. Our one only takes the midde seat in the back of our Astra hatch as well.

mmm Ok I will google both

The Safe & sound looks like it would still be too wide to have another car seat next to it. thats the problem I can also fit an adult on either side of the seats I have when only the baby seat is in the car in the middle position but we need to think of it being another seat. I think I need one where the side wings aren't so wide. I doubt I will find anything.

We have just had this issue. We have 2 x boosters and now the Mothers Choice Chariot reversible car seat, which JUST fits into the gap we had. We have a Laser Sedan. I was looking and the Safe 'n' Sound Compaq Deluxe but could not afford it.

Love