We had a CTS, which is the forerunner to the CT5, maybe a touch larger in fact. It wasn't a large car inside, or in trunk space. An Accord would feel roomier, in part due to having FWD instead of RWD or AWD. Our CTS was the pokiest with the turbo 4 though for me, it had plenty of pickup. It could go when I needed it to go, just not blazing fast. The other odd thing, to me, is the ride comfort was pretty stuff, I'm getting old, it had the Magnaride, which helped a lot with handling no doubt.
The CT4 of course is smaller.