They still have patents; they're just willing to let others use their patented technology, in good faith, without worrying about getting sued for patent infringement. And I'm not sure their open source approach applies to design as well as technology. The design of a steering wheel, rims and trim pieces don't really help to "accelerate the advent of sustainable transport", which is the intent of open sourcing their technology patents. And I recall reading that Tesla did issue cease-and-desist orders to people/companies using their logo or logotype on products without permission, so I would think the same would apply to protecting the design of their cars.
