This could be the rumoured road-legal version of the racer.

The Lamborghini Urus ST-X is the special version of the Italian brand's crossover that's specifically for a one-make racing series that starts in 2020. This spy video catches something interesting. It's not clear whether the modified Urus in this clip is simply a development vehicle for the upcoming competition version or whether this could be the upcoming road-going variant of it.

Gallery: Lamborghini Urus ST-X spy video

The Urus development vehicles in this clip look similar to the existing version but with slight styling tweaks. Lamborghini's engineers tape the seams along the bonnet on the white example, and the low-profile roof rails get a coat of contrasting black paint. The green one gets a modified lower fascia and rear bumper similar to the parts on the ST-X. 

This video also provides a brief glimpse of the wild Urus Rescue Car. It wears an eye-catching yellow and black exterior. There's a roof basket for hauling cargo and a rear-mounted spare wheel.

For racing duty, the ST-X packs the road-going model's twin-turbo 4.0-litre V8 engine delivering 641 bhp and 627 pound-feet of torque. However, it should be quicker than the usual Urus thanks to a 550-kilogram diet that would make the crossover weight around 1,650 kg. For safety, the interior features a roll cage, racing seat, and fire extinguisher.

Building a road-legal version of the ST-X makes sense. The wealthy gentleman racers competing in the one-make series would likely want to experience the performance on the road.

A road-going version of the ST-X isn't likely to arrive until 2020. The racing variant makes a competition debut in October 2020 at the Misano World Final of Lambo's Trofeo series.