We have some Dahon folders.
The really good ones, like the Mariner and the Mu are probably too big. I can fit one in my Bellanca Cruisemaster baggage compartment, and some soft bags around it, The other has to go in the back seat.
We have a smaller Dahon, which has had several names over the years. It might fit, but the bike is too wobbley and too much work to ride any distance over a mile or two.
You might have to get a folder, and then partially disassemble it.
http://www.gaerlan.com/dahon/pack.htmThe Mariner, I got from a gal who, lives on a boat (go figure) she included the Samsonite luggage, and gave us a quick lesson in disassembly to fit it in. But the luggage was heavy.
I crawled into the baggage area to inspect the tail cone and change the battery. It wasn't pretty.
Dahon is the most available brand in the Pacific Northwet. I answered Craig s list ads and saved quite a bit.