My youngest just had his first birthday the other day ( July 22nd)
When he was born , I had the 190E 2.6 which I was very happy with - probably very similar space-wise to the C Class .
I found out straightaway that the pushchair ( we got a 'Bugaboo Bee' ) pretty much filled up the boot all by itself .
The BIG problem was the rear-facing , lie-flat infant carrier which is pretty much obligatory nowadays ( my older daughter is 23 - slight age gap
- , and she had a conventional carry-cot which just lay on the back seat of the Ponton ) . The new infant carriers are of such a length that - in the 190 , almost certainly in the C Class too - restrict the movement of the front seats and need the front seat pushed so far forward as to make it uncomfortable for whoever is in front . I also purchased a base which straps permanently in with the seat belt so that you just clip/unclip it rather than having to belt in and tighten/adjust every time :- this raised the height of the infant carrier to a level that it would not fit in through the door aperture with the carry handle raised ; it was a real PITA . I looked at various infant carriers but they all seemed much the same .
In the end , I needed more LENGTH to accomodate the infant carrier - most saloons and other vehicles didn't look much different to the 190 in that department - so I ended up looking for a LWB S Class and ended up with the W126 500SEL
The long rear doors open wide and it was easy to load/unload the infant carrier through them . I had the car set up with Harris behind me in the carrier and SWMBO travelled on the passenger side in regal luxury ! The twin cigarette lighters in the rear were handy for the electric coolbox to keep milk cool on long journeys and to power the bottle warmer at feeding time !
A new baby is just about the BEST excuse ever to buy a BIG car , and SWMBO will not argue against it when you demonstrate just how much more solid and safer it is , even than the smaller model in the same range ! The S Class also has the benefit of a cavernous boot which would take TWO pushchairs , if required .
Although Harris has now outgrown the infant carrier , and now has a Recaro 'Young Sport' forward-facing seat , I'm not about to downsize back to the 190 - even though it is still in the family !