VW Group weighing the prospect of building a set of roadsters for both the Audi and VW brands. An R4 model would be based on the Audi R4 e-tron Detroit showcar which debuted at the Detroit motor show in January 2010.

VW Group has yet to decide whether to go forward and take a possible Audi R4 model to production, according to an Autocar story.

A production Audi R4 would be based on the R4 e-tron concept car which debuted at the Detroit motor show earlier this year. That Boxster-sized sports model was made out of a lightweight alloy space-frame just like the Audi R8. A larger R8 e-tron concept based on the R8 was also debuted a few months earlier at the Frankfurt motor show.

The rear-wheel drive R4 would also have a mid-mounted engine, as does the R8, and would come available with two turbocharged petrol/gasoline power plants - a 1.4 liter and a 1.6 liter - as well as there being a 2.0 liter diesel variant. Engineers are currently weighing the prospects of a more expensive aluminum frame versus a cheaper but heavier steel unibody structure.

"The reaction to the e-tron concept has been overwhelming. We're weighing up all of the options and possibilities," said an Audi source to Autocar.

VW would also share the platform for the R4 with Audi (as do the Golf/Audi A3 and Polo/Audi A1 models) and build a corresponding roadster based on the BlueSports concept which was first shown at the Detroit show in 2009. Porsche, also now part of VW Group, is also considering sharing the platform for an entry-level roadster slotted beneath its Boxster model.

According to Autocar sources at Audi, the final decision on the vehicle will be taken by VW Group, which owns the Ingolstadt-based premium brand.

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