What are some of the cheaper vehicles sold in the US that can fit three car seats?
(Is a Kia Soul big enough? I can’t judge the size accurately from pictures.)
No, there’s no “good news” being hinted at here. 
One of my mating pair, though, is starting to make noises.
A Pontiac Vibe is quite spacious in the back, with a lot of room for carseats.
Also, the new 2010 Carollas have decent space in the back seat.
I would suggest bringing the carseats to see how they fit, but it sounds like you don’t actually have them yet. I recently crammed my daughter’s forward facing carseat in between a rear-facing toddler seat and rear-facing infant seat in the back of my brother’s Honda Pilot and they all just barely fit. These were all big-ass Britax seats though. There are narrower seats available and I think the right carseat will be as big a factor as the car.
The Ford Focus and Fusion have plenty of room for three kids in the back. My parents have had both, and they will fit three (not particularly large) adults in back for short amounts of time. I’ve been crammed back there, sitting bitch, and it’s not bad for an hour or two (though you have to be on rather friendly terms with everyone else back there). For kids, the space should be more than enough for even long road trips.
Lemme put the size of the back seat of a Vibe in focus a bit more:
Yesterday we were heading to Tim Hortons when we saw my friend Kyle, so we tossed him in the back seat with my friend Josh and myself.
This is a 220 lbs man between a 280 lbs man and me, a 300 lbs man, with two of us being nearly 6 foot 5.
It wasn’t pretty, but it wasn’t uncomfortable.
My experience has generally been that kids in carseats take up a good deal more room than an adult. Both of our cars have three belts in the backseat, but there’s only about 6 inches between the two kids’ carseats.
Ah, fair enough. I’m just old enough that I never was in a car seat, but not yet old enough to have kids either.
I was going to say this too.
Up until recently, I had three kids in booster seats. A Civic was too small for all three seats. My Accord is just big enough, but it was a real PITA to get them all buckled up. There was no room between the seats and the connectors had a tendency to get caught under the seats themselves.
I guess the OP is more concerned with infant seats first. These aren’t as bad because you tend to buckle them once really well and then leave them in. I think you could get three of these in anywhere you could sit three adults. But also keep in mind that you’ll be leaning over and bending in to get that middle kid buckled.
No matter what, I suggest you use a 4-door instead of a 2-door if you are putting kids in the backseat. I had an Integra 2-door and it was a nightmare getting the babies in and out of the back. And this was with those combo babyseat/carrying case things that just snap in.
If you’re talking 3 carseats, a Vibe won’t fit a booster, a toddler, and an infant seat. I know, I’ve tried it in my mom’s Vibe. Ditto with my sister’s Ford Focus. The Pontiac G6 was utterly hopeless.
We have a '96 Volvo station wagon, which has a built-in booster in the middle of the back seat, and we’ve fit two toddler seats or a toddler and an infant seat on either side. It’s a little tight, but doable.
A friend has a Kia Sportage, and he hauls 3-4 small kids around in that. I’ve not been in it, but it seems to work.
Thanks for the info so far.
I was under the impression that a booster seat takes up less room than an infant or toddler seat. Am I wrong about that? (I didn’t mention booster seats in the OP because I forgot my youngest will probably be ready for a booster seat during the timeframe in question.)
I have a Kia Rondo that has an (optional) 3rd row seat. It folds completely flat when not in use for a ton of storage space. It’s a cross between a tall wagon and small SUV. The 3rd row isn’t really useful for grown-ups, but car seats and younger folk fit perfectly well. And you can use one at a time for additional storage if you like.
Edited to add: I got a great deal on it too, because it’s a fairly new model in the US (2007 was the first year.)
I was thinking the booster seats were the widest because they have the armrests sticking out. But after your post, I started image searching car seats to refresh my memory and, yes, they look pretty wide too.
Keep in mind there are four stages: 1) infant seat, 2) toddler seat facing rear, 3) toddler seat facing forward, 4) booster seat.
Depending on your mix of kids, you might be in luck. The infant seats are pretty bulky with the big bassinet handle, but that is only a problem if it is right next to the same type of seat (like in my case). But if you have a mix of seats, you might find a way to arrange them so it works out. For instance, stick the rear facing seat in the middle and that leaves room on both sides for the other types of seats.
**Remember you’ll be seating three for quite a while **The Sunshine Radians are among the narrowest seats in the market, fitting three abreast in cars where others don’t. It allows you to keep your younger children in a five-point harness (safer) longer. Some parents have reported issues with comfort (especially if you do longer trips that include lots of car sleeping). I have not used the Radian, though I have test driven it in the store.
**
Think outside the Bucket *Infant seats don’t “have” to be buckets - the Radian and the Britax Marathon (the Marathon I <have * used) both can be set rear-facing. As my children were slung in a sling or backpack style carrier or carried instead of carted around in buckets, the brief time I used the buckets were rather annoying and was glad to switch to “regular” rear facing seats. Both children rear-faced way past one year, for as long as I could manage (not past two years, though I wanted to).
**
Who else is riding in the car? An additional concern for planning for a new vehicle is adult size. Even if you use a “bucket” style seat, often a rear facing seat such as the Radian or Marathon will take up more space from the front of the cabin than a bucket seat might have.
The invasion of the front seat space can be a major consideration - with one tall adult and one short adult in the family, the reversed seat had to be positioned behind the seat the short adult occupied. Even in mid-sized sedans, the taller adult was uncomfortable in the “short” seat for long amounts of time.
**
How big are your babies?** Depending on the baby’s size, they can’t use a bucket seat longer than nine months or so (my children were quite large, and out grew the bucket seat specs much sooner than that). So you’ll be out of the bucket sooner than you expect, in some cases.
But This is all IME - here’s a place to do research on fitting carseats based on real-world data.
If you can find a Fiat Multipla in the US, They will easily take three kids in childseats or three fully grown adults. As a bonus, I get an average of 45mpg out of my diesel model.
Great post. As a parent of three, I’ll add that fitting the kids into the space is the smallest piece of the puzzle. If the kids are crammed in together, they’ll hit each other with toys/bottles etc, and as they get older they’ll bicker. As they kids start to get older (3-4) they’ll rebel about the lack of personal space, making any trip over five minutes a chore.
The minivans aren’t so popular because they’re sexy looking.
Consider a Crown Victoria or a Mercury Grand Marquis (I think the Mercury is still available new). Dependable, solid cars with huge amounts of interior space, reasonable mileage for their size, and probably the most comfortable car on the road. And you can’t beat the price, new or used.
I asked for “some of the cheaper vehicles” and you point me to $30,000 cars?
And you say I “can’t beat the price”?
O…kay… 
Well, it’s cheaper than a $45,000 car. 
Really, I had no idea that they’d gotten that expensive. The Ford was considerably cheaper, but you can no longer buy them new unless you’re a fleet manager, and I’m guessing that you’re not ready to purchase a fleet. Still, a semi-new one depreciates quite rapidly, making a used one a good investment (not investment in the sense that they appreciate, ya know).
We bought an 8-year-old used Toyota minivan for $7000, a few years ago. Didn’t break the bank, and has been very reliable. We had it fully checked out by our mechanic before we bought it.
There’s an obscure car statistic called ‘rear hip room’ that measures how wide the seat is a tush-level. My father claims to be the only person to ever walk into a car dealership inquiring about said number* (the dealers hadn’t heard of it), but it is a published thing that you ought to be able to find online. This won’t be a magic bullet, since it won’t account for the fact that you can kind of overlap things that are taller with things that are shorter, but it might let you easily eliminate some things that are definitely too small.
*He wanted to be able to fit three adult-sized offspring in the back seat on family vacations, and partially based his car purchase on that.