Just the Facts:
2014 Lexus IS F convertible is caught testing on the Nürburgring.
GS-derived rear suspension is capable of offering rear steering.
Aluminum lower control arms replace stamped steel currently in use.

NURBURG, Germany — The long-rumored Lexus IS F convertible has finally been spotted testing at Germany's famed Nürburgring, but it's what's under the car that is even more exciting.

Before the camoflauged 416-horsepower V8 convertible went for laps around the circuit, engineers put the IS on a lift and forgot to close the garage bay door, giving us our first look at the next-generation 2014 Lexus IS hiding beneath the convertible skin.

The key giveaway is the clearly-visible rear suspension that is all-new. Aluminum lower control arms replace the steel arms used on the current IS F, a nod to the fact that at 3,812 pounds, the current IS F sedan isn't exactly a lightweight. Separate dampers and springs replace the coil-over configuration in the existing IS. In the above photo, the lower spring perch can be seen as the bowed-out section of the lower control arm just slightly inboard of the shock. Furthermore, a new rear toe adjuster or rear-steer ball joint is evident on this mule, something that doesn't exist on the current IS F. See our suspension walkaround of the 2011 Lexus IS F or the above photo of the 2011 model for comparison.

Taking a closer look at the geometry and setup at play here, this next-generation IS's rear suspension is an adaptation of that found under the 2013 Lexus GS. Accordingly, the 2014 IS could employ adjustable damping as well as active rear steering — features that are currently optional on the larger GS sedan.

Inside Line says: The suspension gives it away. Expect the 2014 Lexus IS to break cover in the next 12 months.