i am unable to sinc my 2010 mercedes with my new iphone, any ideas

See if this support document will help. http://support.apple.com/kb/TS3581. Standard issues and usage with Bluetooth and a vehicle is to make sure the vehicle system is in discovery/pairing mode, then put the iPhone in discovery/pairing mode, and continue. See the vehicle owner's manual for information on how to put it into discovery/pairing mode. To put the iPhone into discovery/pairing mode, just turn on Bluetooth.

It often also helps to clear all pairings from car end

Some in-car systems limit the number of pairings and always worth starting from scratch

I just switched my 2011 Mercedes from pairing with my old iPhone 4 to a new 5S and it was a bit confusing (much easier on my wife's Ford Fusion and more capabilities there). Mercedes has downloadable instructions specific to your year/model and specific to your phone. Start with the following link and follow it through selecting your year/model and then click on the picture of your phone (not the check box below the phone) and then download the "pairing instructions" http://www.mercedes-benz-mobile.com