All vehicles that are made must be tested at one point or another. The way that they do this is by getting the cars out on the real roads without anyone knowing. The trick is to cover up the features so that they will not be recognized. Covering up the features allows car companies to keep any new headlight or taillight design more private. This method is common and have been done for a long time. They make the cars look very unattractive so that it does not draw any attention to them (does that mean my beat up car is a test car? No, its just beat up). Fortunately, cars lovers have paparazzi that follow them too. That is why, we get shots of new cars; but without seeing how they really look underneath. But many times, we never get to see the cars drive around unless we live close to areas that manufacture or test these cars, chances are - slim. Some even paint them a weird color or have strange designs on them.
We do get a taste of what the new shape is going to look like, and for some of us, that is enough to get us excited.