I know nothing about 3-D printing, but I think it's pretty amazing that they can produce a car in 3 days with a 3-D printer. Max speed is only supposed to be 45mph so far, so you likely can't take it on any highways.
Currently, the "kids" at NASA are building a rocket using 3D printing technology. They expect to finish in several months. They've been using the printer to make specialized parts for some time now.