My understanding is that this is not necessarily the case although I have heard this stated many times without authority. The 3 days is usually associated with the "cooling off period" under the FDCPA (Federal Debtors and Collectors Practices Act) in which you are confronted by sharp talking solicitors at your home/residence. This doesn't apply when you seek the purchase and you are the person who controls the sale and whether to seek it in the first instance. In fact, the MA Consumer Affairs division warns that there is no "cooling off period" for automotive purchases. Were you solicited at your home? I would not think so.
It would not make sense to have such a law if you set up the sale. If so, then every consumer could drive the car for 3 days and return the used car, significantly devalued by the use. I can only imagine how many people would use this supposed law rather than take a weekend rental rate!
