Pie in the sky. That's where we filed away Audi's flying taxi concept when it debuted at the Geneva Motor Show back in March. But Audi, it turns out, wasn't kidding, and neither were its partners.

Stemming from a joint effort between the German automaker, its sister studio Italdesign, and passenger-jet consortium Airbus, the Pop.Up project envisions a multi-modal form of transportation consisting of an autonomous vehicle that docks into an aircraft so that passengers can be whisked around through the air and on ground. And the project, it seems, it picking up speed.

Now over eight months since its debut, the concept has evolved into the Pop.Up Next, showcased at Drone Week in Amsterdam – albeit not in full size. This concept is a 1:4 scale model with a tiny car docking into a quadricopter not unlike those you can buy from companies like DJI or Parrot (or build yourself from a kit).

"Flying taxis are on the way. We at Audi are convinced of that," said Audi tech chief and Italdesign president Dr. Bernd Martens. "More and more people are moving to cities. And more and more people will be mobile thanks to automation."

While it's working on the Pop.Up Next project with its partners, Audi is developing parallel programs like the Airbus' Voom initiative, which pairs helicopter charters in Mexico City and Sao Paulo with Audis to complete the last mile to the destination, and the Urban Air Mobility project in its home town of Ingolstadt.

In the future, continued Martens, "senior citizens, children, and people without a driver's license will want to use convenient robot taxis. If we succeed in making a smart allocation of traffic between roads and airspace, people and cities can benefit in equal measure."