This is the third new city set I bought this year and also the third city alternate model I have made.
What I did was to change the heavy loader into a car transporter.
The truck can turn easily at least 90 degrees either side even when the back portion is attached. There are quite a bit details in this alternate model. I try to make full use of all the parts available and one of the key detail was to have a functioning stand/support for the back portion when it's detached from the truck.
Pieces from 7900 only and all parts used. Instructions at http://www.brickshelf.com/cgi-bin/gallery.cgi?f=255306