It looks like the RC F coupe we recently spied isn’t the only new F performance model Lexus has in the hopper. Today we have spy shots of a GS sedan undergoing high-speed testing on Germany’s Nürburgring and a number of its features suggest it is actually a prototype for the oft-rumored GS F.

At first it looks like an ordinary GS wearing the car’s F Sport package but peer a little closer and you’ll notice a new lip spoiler up front, unique mesh pattern wheels, uprated brakes and a stacked exhaust design Lexus reserves for its dedicated F cars. The car also looks to be sitting lower than the regular GS.

Expect the final version to feature some carbon fiber panels to help shed weight. Lexus has said the LFA’s complex carbon fiber production process would be used for other models, and where to start than with a dedicated F car.

It’s not clear yet what engine Lexus has in store for its GS F but there have been rumors of a supercharged V-8 or possibly a detuned version of the LFA’s V-10. We’re more likely to see Lexus go with a version of the 5.0-liter V-8 engine destined for the upcoming RC F, however.

This engine is an evolution of the 5.0-liter mill found in the IS F and in the GS F may be tuned to deliver as much as 465 horsepower. In the RC F we expect output to remain similar to the IS F’s 416-horsepower rating. Note, with the arrival of the GS F, Lexus may end up phasing out the IS F after the 2014 model year due to the similar technology between the two.

Look out for a market launch of the GS F late next year, which suggests it will list as a 2015 model. Pricing should fall around the $70k mark, making the car a slightly cheaper alternative to the likes of the BMW M5 and Mercedes-Benz E63 AMG.