Also got to hang out around a Tesla Model S today. Though I did not have my bike with me, it appears from the deep back floor that the tikit MIGHT be able to fit in the rear hatch covered while standing up.
I can't speak to any Mazda 3 except the new 2014 model, which is a complete and total redesign from the ground up.
My old Mazda Protege5 easily swallowed the Tikit. But manufacturers have been significantly shrinking hatchback hatches over the last decade.