I tried Google, but I can't find typical or extreme numbers for how far a car door opens. Â I've heard it's about 3 feet max, but am looking for confirmation.
There is this data from John Allen:
http://www.bikexprt.com/bikepol/facil/lanes/doorwidth.htm
John S. Allen
Technical Writer/Editor,
http://sheldonbrown.com
League Cycling Instructor #77-C
jsallen *at* bikexprt.com
http://bikexprt.com
http://john-s-allen.com/blog
http://bostonbiker.org/streetsmarts