OK, so 3 months ago I transferred all my contacts from my I phone 4 to the RX450.

Since then some numbers have changed.

Can I sync them again or will I have two of everything?

 

I would like to hear this answer too.

I had 640 available spaces in the car and 400 on the phone. I deleted all on the car and then transfered all from the phone. I should then have 600 available in the car, but it was 640 again and a dummy number I put into the phone did not end up in the car.

 

Not sure if this works, delete the phone, and re-add it, then your address book should be empty. Download your contacts again. Maybe??

 

OK, guess I'll have to wait and see if anyone tries this, I can't get to my car for a few weeks yet.

 

I would delete the phone like wyau01 suggested. I did that when I switched from the iPhone 3GS to the iPhone 4. Downloading contacts took seconds. Very simple.