RICHARD BLACKBURN October 16, 2009 – 12:47PM

Images have appeared on the internet of a new baby brother to the R8 supercar and its electric. By RICHARD BLACKBURN.

Audi will build a production version of its e-tron electric supercar concept.

Web reports suggest the zero-emission sports car, to be called the R4, could hit the road as early as 2011.

And a report on UK website Auto Express says the R4, a smaller version of the R8 supercar, will also have petrol-powered versions.

It says the new car could share a platform with the next-generation Porsche Boxster and Cayman, given that Porsche is now part of the Volkswagen Group, which also owns Audi.

The R4 will slot in just above the TT coupe in the Audi range, and will most likely share some petrol engines with the TT.

Audi’s US boss Johan de Nysschen told US industry journal, Automotive News, that “running examples” of the R4 would be on the road in the next two years.

The low-slung, lightweight e-tron concept, unveiled at last month’s Frankfurt motor show, had electric motors at all four wheels and could sprint from 0-100km/h in just 4.8 seconds.

Its lithium-ion battery pack, which was positioned where the engine would go on petrol versions, could be recharged from a domestic power point in about eight hours and had a range of about 250km.

Audi is developing a rapid-charging option that can recharge the battery in about two-and-a-half hours.

It is also working on a home-based wireless charging system where the car starts re-charging as soon as it is driven into the garage.

The concept car’s top speed was limited to 200km/h, but the production version is tipped to have a slightly higher top speed.

Photos posted on Auto Express show a canvas-roofed Targa version of the R4, although a convertible is also believed to be on the cards.

Audi will use a lightweight aluminium frame and carbon fibre components to keep the car’s weight down, while it will also have regenerative brakes, which capture kinetic energy usually lost when a car slows down.

The e-tron has a similar weight distribution to the R8 on which it is based, with weight split 42:58 front to rear.

By default, 70 per cent of the e-tron’s drive goes to the rear wheels, while 30 per cent is applied to the rear wheels.

But in keeping with Audi’s Quattro four-wheel-drive heritage, the drive can be sent to the wheels with the most grip to improve traction.

And the car takes advantage of the electric motor at each wheel to enhance handling.

The on-board computer can deliver microsecond-long bursts of either power or braking force to individual wheels to eliminate understeer.

No pricing information is available on the R4, but with the most expensive TT costing about $100,000 and the cheapest R8 going for $260,000, there’s plenty of room for the R4.

The R4 isn’t the only electric German supercar on the drawing board.

Mercedes has an electric version of its new SLS AMG Gullwing in the pipeline, while Porsche has committed to hybrid and electric versions of its sports cars.