Usually, once you've signed on the dotted line and driven away from the dealership, you're stuck with the options you chose during the purchase process. Mercedes wants to change that, for some options at least.

Mercedes-Benz will use its Mercedes Me connected-car platform to offer specific options as after-the-fact purchases. Available on the A-Class, B-Class and GLE-Class -- the vehicles rocking the flashy new MBUX infotainment system -- buyers will be able to use Mercedes Me to purchase digital radio, smartphone integration and navigation options after purchasing the car.

It's a relatively straightforward process. If a car is connected with Mercedes Me and has a functional data connection, owners can go to the Mercedes Me store and purchase the aforementioned options with just a few clicks. Mercedes-Benz says this can be useful when an owner forgets to check specific options boxes at the dealer, or it could be beneficial to second owners who want more tech than the first owner did.

There's also another huge benefit for Europeans in there, too. Digital radio will become mandatory for new vehicles in the EU starting in 2020, and outfitting an older car with that tech is likely to boost its resale value slightly. So, while owners may not want it now, it could become useful later.

Not every buyer specs their vehicle from scratch and waits for the factory to build it. Dealerships maintain a stock of prêt-à-porter vehicles, optioned in a way that buyers will hopefully appreciate. If every car on the lot lacks navigation, but a buyer doesn't want to wait for a car to be built at the factory, Mercedes Me can get around that problem.

Mercedes' MBUX infotainment system has proven mighty impressive in our tests. In our recent review of the A-Class Sedan, we found it to be responsive and full of features, but everything's laid out in a way that doesn't make it feel overwhelming. Its "Hey, Mercedes" digital assistant is a nice touch that can take natural-language commands and translate them to actions like adjusting the climate control or turning on the heated seats.

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