The car has been built by Tommi Makinen Racing in Finland with the blessing of Akio Toyoda, the president and CEO of Toyota Motor Corporation.
The car is believed to be running at a private test in Finland today - with more news expected on Friday.
Toyoda is present in Jyvaskyla this week to meet with Makinen and WRC officials.
The GT86, which is being described as a test mule, has nothing in common with the Yaris WRC that has been produced by Toyota Motorsport GmbH in Cologne.
It is also independent of the GT86 CS-R3 revealed by TMG this week - and will run at next month's Rally Germany for the first time.
The directive for the four-wheel drive GT86 has come from Japan and AUTOSPORT understands it is indicative of a cooling of relations between TMC and Cologne.
- Akio Toyoda