Aston Martin DB 9 2010 Manual page 204

(Q) The position of the vehicle on the map is incorrect after the
vehicle battery has been disconnected.
(A) If power has been cut from the GPS antenna, it can take more
than five minutes for the GPS signals to be received correctly and the
position of the vehicle to be calculated.
(Q) The map image does not correspond with the real situation.
(A) Factors such as the constant expansion and rebuilding of the road
network, new traffic regulations constantly being introduced etc.
means that the digital map database is not always complete. The
information stored in the maps is constantly being developed and
updated. An Aston Martin Dealer can provide further information.
10.34
(Q) The scale of the map sometimes changes.
(A) Scale is affected by vehicle speed. At speeds over 87 mph (140
km/h) the largest possible degree of magnification is 820 ft (250 m).
Once speed decreases to 74.5 mph (120 km/h), the system is once
again able to show all degrees of magnification. If no detailed map
information is available, the degree of magnification automatically
selected regardless of speed.
(Q) The expected menu option is missing.
(A) Look at the settings that have been made. Select <Reset to
default> to restore the original settings.
(Q) The system shows the route I am already on when I request
Calculate new route or Detour.
(A) The system cannot find a good alternative to the current route.
(Q) The vehicle symbol on screen jumps forwards or spins.
(A) The Navigation system may need a few seconds to sense the
position and movement of the vehicle before driving off. Set both the
Navigation system and the engine to OFF. Start again, but stay
stationary for a while before starting to drive.
(Q) I'm going to make a long journey but i do not want to specify
a special destination to the Cities I am thinking of travelling
through. How do I most easily create an itinerary?
(A) Specify the destination directly on the map using the hairline
cross. The system automatically guides you to the final destination
even though you are driving beside the intermediate destinations.