Porsche is working on a family of three heritage versions of the 911 and the first one was the 911 Sport Classic. Word on the street is next in line is the 911 ST, which is expected to debut at some point this year. We have a batch of new spy photos of that 911 and you can browse through the photos in the gallery attached below.

This may seem like a regular 911 prototype but there are a few signs that tell us it is indeed the new ST version. Take for example the double-bubble roof, which is a touch we know from the 911 Sport Classic, the first member of the 911 heritage family. Centre lock wheels can be seen on all four corners and this is a feature we’ve already seen on the Porsche 911 GT3 Touring.

Gallery: Porsche 911 ST spy photos

Speaking of the GT3 Touring, the 911 ST will actually be based on that vehicle. If Porsche decides to keep the engine without tweaks – and this is what various sources say – the ST model will have a 4.0-litre flat-six engine under the bonnet with an output of 502 bhp (374 kilowatts) and 346 pound-feet (469 Newton-metres) of torque. An automatic transmission seems certain at this point, though we don’t know whether the Stuttgart-based automaker will also sell a three-pedal version.

The 911 ST will be sold as a special edition model inspired by a small-run racing model from the early 1970s. The latter probably serves as an inspiration for some of the design features, including the Porsche Heritage emblem that is likely hidden under that black circle on the engine mesh cover at the back. Don’t expect huge design changes over a standard 911 GT3 Touring but there will surely be some retro-inspired touches here and there.

If our information is correct, we expect to see the 911 ST debut this year. This isn’t going to be the most exciting 911 heritage version, though, as there are reports about a revived 911 Carrera RS coming after the 911 ST.