I have a friend of mine who is getting rid of the seat as his kid has just grown out of it (he lives 6 hours away, so I can't just grab it to check it out). It's exactly the right price as it's free and he bought it brand new 8 months agp. The stroller I have will fit it so I'm not worried about that either. I'm just concerned that some seats may/may not fit with the Sante Fe front seats in their furthest position back.
How reclined do you normally have your front seats? If you have them pretty upright you'll have a lot more room for a seat behind you than if you have them all the way back on the tracks + reclined a good bit. A lot of people tend to drive with their seat more reclined than what they need it - which actually isn't safe for the driver or passenger either, so it might be something to consider in being able to get more room for an infant seat.
I brought up a picture of the 2010 Santa Fe on ebay motors. This one has a cloth interior and I'm not sure if that's what your's is or not, but the bigger issue when it comes to compatibility with the maxi cosi is the vehicle seat slope and the length of buckle stalks or depth of UAS anchors.
You're most likely going to want to put a carseat in the center seating position since it will have the least effect on the front seat passengers in that position. But in order to install the seat in the center, you'll have to do a seatbelt installation. And looking at the length of your buckle stalks, and being very familiar with an older model year interior, I can pretty much guarantee that the maxi cosi will not install tightly with the seatbelt.
If the seat will fit behind either the driver or the passenger, then you might have a chance with UAS - I don't know the depth of the UAS in the 2010 santa fe, so I can't say beyond doubt that it wouldn't fit, but looking at the slope of the seat - and there really isn't much to speak of, I'm really unsure if you would be able to get a tight install even using the lower anchors.
The Maxi Cosi unfortunately has some major compatibility issues with a lot of vehicles, and it's because of the way the belt path on the base is shaped. Basically the way the plastic is molded it creates big incompatibilities with buckle stalks - and even the adjuster mechanism on the UAS strap runs in to the same problem if the vehicle seat is flat enough to not need to adjust the foot on the base.
Are you able to go in to a store that carries it and try it out there before committing?
Otherwise I'd suggest giving the Graco Snugride 35 a try - I know it installs really well with the seatbelt in the center there and depending on where your front seats sit and how they're reclined, it may sit right between the front seats without you needing to adjust them at all. The handle can be left up in the vehicle making it take up less room, and it has a built in lock-off which makes seatbelt installation really easy.
Another seat which might fit is the Sure Fit - it comes on the Eddie Bauer endeavor travel system, but is also sold as the complete air infant seat. I'm not sure if that one would be compatible with your stroller though - while I'd be pretty sure the Snugride 35 would be since Graco's are compatible with most of the higher end stroller brands.
I'd not even bother trying an evenflo. They take up a lot of room and the handle has to be down in the vehicle with an additional 1.5" of clearance behind it. I'm sure it would install fine in the center - but I doubt you'd get the clearance room to put the handle down without having to seriously adjust your front seats.
