Will the Thiel CS2.4 fit in my car?

put em both in the back seat lying down

Probably. Interior width of your BMW is 54” and the Thiels are a tad over 41” tall. You will have to take them out of whatever packaging the seller shipped them to you in however as I’m pretty certain they won’t fit still in a box.  Good luck finding an easy way to dispose of that ... 

I plan to fold down the back seat.  The Thiels is a bit narrow so I will place one on the side in the trunk length-wise.  The front passenger side should fit one.

Is this really a serious question?
Hire a small van, If in doubt.....actually be safe hire one. Will probably cost you about a $100 or less with no hassle. Why take the risk? 

You don’t know the H x W x D, plus the gross weight of the containers / crates. Best to get a van - - and a friend to help you load and unload them. Carrying and moving shipping crates can easily be a two-person task.

Been there, done that, got the T-shirt  for my  2.7s