MB USA offered it for a few years in the States. Most MB "Nuts" despised it since it only covered the services as per the FSS computer. Most of us service our cars with much greater frequency, and that was not covered. Now, it did cover brake pads/discs and so on, but only if they wore out before the end of the warranty. Heck, in Canada, MB used to (not sure if they still do, but did when I bought my car) have a 40K complete warranty that covered every single thing, including brake pads/etc. Just not fluids/filters, which are not expensive.
I don't find routine maintenance a significant cost and I am LOATHE to be forced to return to the dealer.
I wonder if included service might be a strong selling point in the one-post-above entry level, the Mazda3 and Corolla slot? Many of those buyers are buying a new car to simply control expenses. They find a monthly payment and warranty giving peace-of-mind. Of course, the sticker would have to rise in a price sensitive category, but you then would be able to roll up all your service costs into your financing/lease.
Food for thought...