Elon Musk has a lot of projects going on – of which Tesla is just one. Another is The Boring Company, which is in the midst of developing a high-speed underground transportation network.

The superfast subway will eventually have its own unique cars. But those aren’t ready yet. So to test one of its new tunnels and the rail system it’s placing therein, The Boring Company borrowed a vehicle from one of Musk’s other ventures. Namely, a Tesla Model X.

The Boring Company released this short (very short) clip of a Model X being catapulted through one of its tunnels. It may not be quite as unusual as, say, launching a Tesla Roadster into outer space in one of Musk’s SpaceX rockets, but it’s an interesting confluence of two of his projects, just the same.

As The Motley Fool aptly points out, The Boring Company is working on tunnels for two applications that are both similar (in concept) yet very different (in practice). The more evocative of the two is the Hyperloop, a sort of underground bullet train that will utilize vacuum-pressurized tubes in which these specialized transportation pods will be launched.

The other is a simpler Loop that won’t be pressurized and will be used for inner-city transportation. It’ll still be pretty fast – targeted for around 150 mph – but won’t be as fast as the vacuum-pressurized Hyperloop (which will travel at speeds approaching the sound barrier at 768 mph).

Either way, they won’t be using Tesla’s electric vehicles as the cars within the tubes once they’re complete. But the Model X seems to make for a pretty good stopgap in the meantime.