Stay on Top of Emerging Technology Trends Get updates impacting your industry from our GigaOm Research Community

In November, Ford Motor Company(s f) hit a critical milestone: its 10 millionth Sync-enabled vehicle rolled off the assembly line. But that doesn’t mean that Ford has built 10 million connected cars. Sync in its most basic form is a voice command-and-control system. AppLink, the in-car connectivity platform companion which allows apps in your smartphone to run in the dashboard, has only made it into 1 million Fords since it launched in 2010.

Ford, however, said on Friday that it plans to boost that number considerably in coming months by retroactively installing AppLink in as many as 3.4 million Sync-enabled vehicles already on the road today. Ford hasn’t yet revealed any details about which vehicle models will be eligible for the upgrade or when they would receive it. It appears that process will involve a simple software download, though its unclear whether customers can install the software themselves or must go to the dealer. We’re likely to hear more at CES next week.

The fact that Ford can flip a switch in 3.4 million vehicles and turn them into connected cars is impressive, owing to the way AppLink was originally implemented. Unlike many other connected-car infotainment systems, AppLink is a fairly lightweight platform. It’s basically a user interface and thin software client designed to interact with the smartphone. The handset not only hosts the apps but also provides the critical mobile data connection back to the internet.

That smartphone-centric approach has allowed Ford to put its connected car platform in more affordable vehicles and build up a sizable developer community and app catalog (AppLink hosts 60 apps today and is growing). It’s also made every generation of apps backwards compatible to every AppLink system launched since 2010, according to the company. And as Ford revealed today, AppLink is flexible enough to make it an aftermarket upgrade in millions of currently unconnected vehicles.

For the bigger picture on how AppLink fits into Ford’s ambitious connected car plans, be sure to check out my recent profile of Bill Ford, the automaker’s executive chairman. In a detailed interview, Ford explained how vehicle connectivity, autonomous driving and electric power-trains will drive a new wave of automotive innovation not seen since his great-grandfather Henry Ford built the Model T.