The battery-powered Smart Fortwo Electric Drive has a range of 63 miles per charge, making it a great city car, but not the sort of thing you’d use for a vacation.

Even if you managed to string together an itinerary that worked around the 8-hour stops required to recharge it, the car’s small cargo area and two-seat layout mean you couldn’t carry all that much stuff along with you for the trip, anyway.

But what if you could pack some extra car?

That’s the idea behind the Dock+Go system from Swiss automotive design firm Rinspeed that was unveiled this week at the Geneva Motor Show.

The company has created a series of modules that plug into the car and offer a variety of functions to meet specific needs. Each is mounted on a single axle and turns the Smart into a six-wheel car when attached. One of these “backpacks on wheels” is simply a larger battery pack that offers more range, while another carries a small internal combustion engine that works as a generator when the battery is depleted and allows for even longer trips, similar to the way the Chevy Volt operates. A hydrogen fuel cell is also envisioned. Multiple packs can be clipped together to create the world’s smallest and nearly unstoppable eight-wheeler.

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For even more specific customization, there is also a pack that turns the car into an electric pizza delivery vehicle, complete with an isothermal box to keep food warm, and one fitted with audio equipment and speakers that let the car act as a mobile DJ station.

This isn’t the first time someone has applied the concept of a steam locomotive tender to an electric car, and with range anxiety a continuing theme among the electric car averse not likely the last, but the system looks like the most well-integrated to date.

Unfortunately for would-be green globetrotters, as with many of the cars on display in Geneva, Dock+Go is merely a concept at this stage, so plan your trips accordingly.

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