Question new here - recommendations on narrow car seats

Hi there,
I just stumbled across this forum but it looks like I'll be able to get a ton of info. Here is the scenario

I am bound and determined to drive small, gas efficient vehicles. Right now we have a 2007 Toyota Yaris sedan (Shoulder room 51.6/50.2 acc to their site if that is the correct numbers). DD1 is 28 months, 26 lbs and is in FF Britax Marathon behind passenger seat. DS2 is 9 months, 18 lbs, 28" about and in Britax Companion behind driver. We think we might have another baby sometime in the future, probably when DD1 is ~3.5 and DDS is a little under 2.

So, what are my options? Are there seats that would fit in this back seat or would we have to upgrade slightly to a car with a little larger back seat (but still efficient)? I'm totally clueless as to what even exists. I don't mind paying $ for something quality. I had someone talking to me about Sunshine carseats - are they top end? mid range? narrow? What else do people use? Or what other cars do people use that are very efficient and fit 3 across? (If you could give MPG that would be great).

I feel like I'm entering foreign waters here.... Help!

Stick with 2 kids and the world is your oyster We do have a successful 3 across thread. I'll link you to it in a bit. Also, the Sunshine Kids Radians are the narrowest seat out there, but often it's about how they puzzle together. They can be difficult to impossible to install in some vehicles, and rear facing they take up alot of room front to back.

I understand about wanting a small, more gas efficient car. And 3 carseats in the back is doable in many vehicles, but to me, and of course this is only my opinion, 3 kids = minivan unless it's an emergency!

http://www.car-seat.org/showthread.php?t=33226

I checked carseatdata.org and there were only 3 vehicles listed as fitting the Yaris - one listed the First Years True Fit, the other 2 entries were for infant seats. What seats are you using now, did you say? Have you tried them in there at all?

ETA: I got carried away. You're wondering what your 3 across options in the Yaris are, is that correct?

I haven't actually tried 3 seats in it yet - basically just wondering if anyone has had success in smaller cars and what seats they use. I have two Britax seats now - a Companion and a Marathon which I clearly won't be able to keep using (I don't think) if another comes along.

So yes, wondering what options are available to me in a Yaris and/or any other small car. What else do people even use? I'm totally clueless....

Thanks!!

This thread may be helpful to you.

I would invest in a Radian when your baby is ready to move out of the infant seat. Then you can see how it fits side by side with the MA you have and get an idea of if you'll need a slightly bigger vehicle or not. There's a member here who has 3 across in a Corolla(?) I believe, not sure how that compares to the Yaris.

thanks for that link to the other thread up there, that is just what i was needing!