The Di Blasi R7E folding motorbike design has remained mostly unchanged for the last 25 years. While that's a indicator of simple, solid engineering, it also means very few improvements have been made—I'm looking at the 50cc 2-stroke engine, specifically, and its need for a 50:1 ratio of fuel and oil. (Two stroke engines tend to cough out a lot of dirty exhaust, as well as noise.)
But there's no denying it's a cute and clever little runabout, capable of being folded down into a block that takes up less than five cubic feet of storage. It still weighs about 60 pounds, but I bet it's one of the only bikes you can have shipped to your door for under $100.
While they're built in Italy, an American company, Folding Motorbike, Inc., has taken to importing them, although they don't list their prices on their ridiculous flash website, nor do they discuss street legality. Another company is selling them on eBay for three grand, which seems like a lot of money when you can buy a slightly used one in the UK for well under that. Considering how inexpensively one can pick up the far more stylish Honda CT70 Trail Bike on eBay, albeit in various states of disrepair, the ability to fold your little two-stroke down into a block will need to be pretty important. Which is why there is also the R7ES model, I suspect, which replaces the carbon steel frame with one of stainless, the better to resist corrosion when stashed aboard a boat.