When I worked in restaurants, we had to open "walls" like those folding doors all the time, and it was a pain. If you **** them just a little bit they bind (there wasn't a track on the bottom, just the ceiling. I can't imagine there'd be lower track with those folding carriage house doors, as it'd fill with dirt, sand, rocks, etc.)
Chances are pretty good that you aren't going to be parking a car smack in the middle of the new garage... if you do, it'll only be for a little while.
I'd go with the two doors, and the small section of wall between them, and then take advantage of that section of wall between the door: it's the perfect place for an old-time wall-hanging thermometer (like Mail Pouch, or any number of soda thermometers... I have a Hire Rootbeer one hanging), a fire extinguisher, and a small garbage can (I have small vintage Texaco oil drum there). I've also seen nice vice tables mounted on the wall between doors--steel table top just a little bigger than the vise, angle iron supports going down.
There's a lot you can do to work with the twin carriage doors.
-Brad