Bmw roadster cruise control my 06 z4 does not have cruise, can it be added

you can find many sources for an add-on cruise control system.  go to google.com and enter "add-on auto cruise control" (omit the qoutes).  you probably have to have the system installed by a local mechanic unless you are above average mechanically inclined. be sure to do you homework on the system you want to purchase. I have added these systems to several cars and the work will.  if the one you add will not hold a speed above 65 mph. change the settings to the next higher number of cylinders. ( 4 to 6 or 6 to 8). this is usually done with small jumpers similar to the ones in a computer memory disk.