I've just done this upgrade to MK IV and one of the main reasons was to get the 3D view but it is not automatically enabled. I found this info on another site that credited it to a member here on X5 world. Maybe it should be in the front page guides. It could be there already but I couldn't find it !!

Do this:

1) Push the "MENU" button to get to the the main menu.
2) Scroll to the "SETTINGS" (or "SET") menu selection and click the knob to select it.
3) Push and hold the "MENU" button for about 8 seconds to enter the GPS Service Menu.
4) Scroll beyond the bottom to a 2nd page, where you will get the Perspective option.
5) Click the knob on the Perspective option to enable it.
6) Once the Perspective feature has been enabled in the GPS Service Menu, you can switch it on by going to the "Map Positioning" menu (i.e. the popup menu where you select "Pointing North" or "Travel Direction") and selecting the new "Perspective" setting that now appears there.

Alternately you may wish to part with some hard earned cash and purchase this information on eBay