cost of ownership. Other costs could be saved, for example, there is no need for an energy-intensive ventilating system, since cars are not driven inside and human cashiers or security personnel may not be needed. For naturally ventilated car parks structures, the ventilation equipment is not needed. Automated car parks rely on similar technology to that used for mechanical handling and document retrieval. The driver leaves the car in an entrance module, and it is then transported to a parking slot by a robotic trolley. For the driver, the process of parking is reduced to leaving the car inside an entrance module. At peak periods a wait may occur before entering or leaving, because loading passengers and luggage occurs at the entrance and exit rather than at the parking stall. This loading blocks the entrance or exit from being available to others. It is generally not recommended to use automated car parks for high peak hour volume facilities. Additional factors that need to be taken into consideration are: Fear of breakdowns (How does the user get the car back) Maintenance contracts needed with suppliers Automotive factories and car dealerships often use automated car parks to store inventory, which makes best use of space if they operate in urban areas, plus the car park may be decorated to promote the brand. For instance at the Autostadt there are two 60 meter/200 ft tall glass silos (AutoTürme) used as storage for new Volkswagens. The two towers are connected to the Volkswagen factory by a 700-metre tunnel. When cars arrive at the towers they are carried up at a speed of 1.5 metres per second. The render for the Autostadt shows 6 towers. When purchasing a car from Volkswagen (the main brand only, not the sub-brands) in select European countries, it is optional if the customer wants it delivered to the dealership where it was bought or if the customer wants to travel to Autostadt to pick it up. If the latter is chosen, the Autostadt supplies the customer with free entrance, meal tickets and a variety of events building up to the point where the customer can follow on screen as the automatic elevator picks up the selected car in one of the silos. The car is then transported out to the customer without having driven a single meter, and the odometer is thus on "0". Automated car parks have been popular