I'm all for awesome engineering projects, in which this project is not deficient, however if this thing can be street legal then I don't understand why so many other cars are not allowed to be. Even when this thing is working as intended. it's shooting hot flames out the back.
Most laws around street legality center around certification of the chassis, safety equipment, and emissions. Don't run the jet engine during a smog test, and prove that all the necessary safety equipment function (signals, airbags, seatbelts, etc), and you're going to pass. This is why most kit cars depend on a "donor" chassis that gets stripped down and have the new car built on top of.
You wouldn't happen to work for a large German automotive company with the letters V and W in the name, would you?