reimburses up to $15 a day for car rental or transportation costs including taxi, bus and train fare (up to $450), while your car is undergoing collision or covered repairs. Coverage of up to $100 a day (up to a limit of $3,000) is available for an additional cost. Even if you have this coverage, some car rental agencies may refuse to rent to you if you are under a certain age, are a poor credit risk, do not have an acceptable credit card or have an unacceptable driving record.
Your Collision, Limited Collision and Comprehensive coverage will apply to any other car you rent or use with the consent of the owner, except a vehicle owned or regularly used by your spouse or a house-hold member.
If you can afford to take a cab or rent a car when your car is in the shop for collision repairs, you may not need Substitute Transportation coverage.
Source: Massachusetts Department of Insurance