The firm has given the green light to an official engineering feasibility project to explore whether the car could be made.
The Q50 Eau Rouge - named after the infamous corner on the Spa race circuit - was shown with a twin-turbo 3.5-litre V6 shoehorned under the bonnet.
"This is now an official project," said Infiniti boss Johan de Nysschen.
Infiniti plans to build at least one prototype to explore the engineering realities of fitting an engine designed for a four-wheel drive, transaxle-equipped coupé into a four-door saloon with a conventionally sited transmission.
“There are many things to look at, details like the different vibration harmonics that result when you take an engine designed for one application and fit it in another,’ said de Nysschen.
Infiniti will also test durability and the practicalities of manufacturing. "This is quite a complex process,"he added.