It looks to me as though the law doesn't apply only to *new* car sales, but rather to all car sales, both new and used. In cases where new car sales are meant to be treated differently then used car sales, the law appears to specifically spell out the distinctions.
For example the law makes it clear that dealers have 30 days from the sale of a used car to file the registration papers, but they only have 20 days to do so from the sale of a new car. However, the section dealing with the 6-month validity window for the report-of-sale sticker doesn't make any distinction between new car sales and used car sales. So, it's conceivable that selling the car back to the dealer, only to re-lease it all over again, might actually meet the requirements..