There is a tubular 'roll cage' type of thing going on with it, reminiscent of rally cars and kit cars. Given that rally cars have roll cages and normal cars do not, I for one look on a roll cage as a good thing, even if the rest of the box is prototype bits of plastic.
Part of a safety rating is the effect a car has on pedestrians. People can get killed by hood ornaments even at a relatively low speed. To date very few cars have been specifically designed with pedestrian safety in mind. One of the few was the Austin Metro and that was a long time ago. It does look as if the Google people have thought of pedestrian safety - it is a big part of the self driving concept and it also appears to be part of the implementation. I wouldn't be at all surprised if the final implementation of the driver-less car is in a whole new level of safety compared to regular cars with the difference being like the difference between 'tame' and 'wild' animals.