The Audi R8 E-tron is the road-ready pinnacle of Audi's research and development into alternatively powered cars.
It's an R8 Coupe powered by a large 49kWh battery, which feeds two electric motors located on the rear axle. These produce a combined 375bhp.
Audi had originally planned to put the R8 E-tron into production, but has since decided there's an insufficient business case, despite Mercedes' recent unveiling of an all-electric SLS.
Audi says that each of the existing 10 E-trons currently cost more than 1 million to create.
What's the 2013 Audi R8 E-tron like to drive?
Our drive was restricted to a short period on track, but it gave us a chance to test the E-tron's performance and handling capabilities.
Producing 605lb ft of torque requires a lot of batteries, so it's no surprise the E-tron tips the scales at 1780kg 200kg more than a V8-powered R8.
That said, Audi has had to work hard to keep the disparity at 200kg. For instance, the body is totally new and built from aluminium and carbonfibre.
Handling is helped by arranging the batteries in a T-shape, while also keeping them low and centrally located for the optimum balance and centre of gravity.
Virtually all the torque comes from standstill, and the E-tron can accelerate from 0-62mph in just 4.2 seconds and on to an electronically limited top speed of 124mph.
Another departure from the regular R8 is that power is sent only to the rear wheels. The revised suspension helps to keep body movements under control, but it's the host of onboard electronics that really conceal the E-tron's extra weight.
Left in 'Efficiency' or 'Auto' mode, the stability control system is quick to sort out any wheel slip, but switching to 'Dynamic' reduces the system's intervention just enough to let you have some fun. This more aggressive mode also sharpens the throttle response and weights up the steering.
The steering feels best in this weightier setting and is consistent and accurate. However, the E-tron doesn't feel quite as sharp on turn-in compared with its petrol-powered counterpart.
Stopping is just as effective, though. The E-tron combines the stopping power of its energy-recuperation system with that of ceramic brakes to bring you to a standstill surprisingly quickly.
Whichever mode you're in, the advanced torque vectoring system does a great job of helping you corner as fast as possible. It actively brakes the inside rear wheel while increasing power to the outside one.
Two paddles sit either side of the steering wheel, but the single-speed E-tron requires no gearchanges. Instead, the paddles allow you to adjust the aggression of the energy-recuperation system.
Our super-smooth track drive didn't give us a chance to assess the E-ton's ride, but while there was little wind noise at speed, the lack of an engine note meant road noise was a constant companion.
What's the 2013 Audi R8 E-tron like inside?
One of the main weaknesses of the regular R8 is its infotainment system, which is starting to show its age as fresher competition reaches the market.
However, the E-tron is different; it has the very latest version of Audi's MMI system, which looks and works far better, and also incorporates the E-tron's selectable drive modes and energy information.
Also new is the chunky metal 'gearlever' although this doesn't actually change gear, it allows you to select 'drive', 'neutral' or 'reverse'.
The rear compartment that contains the battery is sealed meaning there's no rear window so Audi has fitted a rear-view camera, which shows the image on a screen and takes the place of a traditional rear-view mirror.
The dials have changed, too; they now display the amount of charge left in the battery and how much power is being produced by the electric motors. Between the dials is a small colour screen depicting where the power is being directed.
To round things off, the comfortable Alcantara-covered sports seats are the same design as those in the regular R8, but are made from lighter carbonfibre, while the cabin also gets red highlights on the doors and dashboard.
Should I buy one?
You can't, but the R8 E-tron is more than capable of changing any negative perceptions you may have about electric cars.
It looks fantastic and is great to drive, while the interior upgrades make it feel more modern than a petrol-powered R8.
The E-tron could even fit into real-world life reasonably easily, because it's charged via either the mains (12 hours) or by using a special DC adapter, which takes less than an hour.
That said, a maximum range of 134 miles between charges would have been a likely stumbling block for many buyers.
The E-tron, therefore, remains a mightily impressive showcase of future technologies that will no doubt make their way into more mainstream Audis of tomorrow.
By Rory White
Engine size Two electric motors
Price from n/a
Torque 605lb ft
0-60mph 4.2 seconds
Top speed 124mph (electronically limited)
Maximum range on a single charge 134 miles