I have had two large car seats in mine. I am 5'10 and have been able to have either one behind the driver seat with no issue.

Peg Perego Primo Viaggio SIP Infant Car Seat (Infant)
Britax Convertible Advocate CS 70 Car Seat (Todler)

The Britax is a tight fit in the middle of the back row, facing backwards. Facing forward it is no problem at all. When in middle, it does not effect the front passenger seats at all.

 

I do. I have a Chico rear facing infant car seat. I wouldn't say there is ample room but it works. I will take a shot or two to show ya the fit.

 

I have a Baby Trend in the back seat, I'm 6'3" and it fits fine. I used to have a 2010 Taurus SHO and the only place the same baby seat fit was in the middle. Before I bought the S60 RD, I put the baby seat in to make sure I had room. Here are some pictures:

Edit: Actually, I can't add photo's. PM me and I'll email them to you.

 

I have a Britax something in the back of mine ... and we are going to need a mount for #2 come June. No one in the family is over 5"4 so there is room in the S60. My wife's car is a Honda CRV so we can always use that when we need more space.

Saying that, and I DO love my S60.... I leased it in December when my wife was pregnant but we didn't know! I'm wondering if I would have made another choice had we known... Oh well, 33 months to a new car.

 

It's friday afternoon so instead of doing work....

Britax child seat installed behind drivers seat. It sure looks like there is a lot of room in this picture. Keep in mind I'm 5'4 so the driver's seat is a little more forward than a typical guy's height would probably be.

Routing the rear LATCH connector is a little tricky but not impossible. As seen in the photo below, you can string the belt underneath the headrest (red circle) so you can attach it to the anchor (red arrow). Let me save you some time figuring this out. First lower the head rest using the button on the center stack. This will make the gap between the seat and headrest bigger. Once you are all done LATCHing, push the headrest back into position. You will have to push harder then normal to get it locked. Then, ever don't press the headrest release

 

Guys, thank you all for the great info and pics. It is much appreciated.

Even though the rear legroom is pretty tight - 33.5" - I was actually quite surprised by how spacious the back seats are. I guess you can't just go by the hard numbers and it often depends on the actual design of the front and rear seats themselves. My former B7 A4/S4 had exactly the same RLR measurements but were much tighter in the back than the S60 is. It looks like a standard baby seat fits back there quite comfortably.

 

This newborn seat is large but it works.