In this process, it is always important to remember that the Will does not really have any legal significance until it is "allowed" or "proved" by the Probate Court. Once the Will is allowed, you will get a document from the Probate Court essentially telling the world that you and your bother are the duly appointed executors, and are therefore authorized to act on behalf of the estate. This document in MA in called a "Certificate of Appointment". It is your "license to administer" the estate.

So while it may make perfect sense to you that the registry should re-title the car based on the plain language of the Will, the registry is not interested in the Will. The registry only wants to see the paper that authorizes you to act on behalf of the estate.

The good news is that if you only have to deal with a motor vehicle, then you are eligible to use a very streamlined process called a "voluntary administration". You file an original death certificate with the court, along with the original Will, your petition and the filing fee ($65 I believe) and about a week later you will get the same petition back - signed and sealed by the Probate Court. That will be your Certificate of Appointment - and that is the document you need to bring to the registry. Your insurance agent should be able to tell you what other documents you will need to bring to the registry (signed title, check for registration, RMV-1, etc.).

I have posted a more involved description of the Voluntary process in the recent past.

Good Luck.