A lot has changed since we last tested Audi’s all-electric sports car, the e-tron.

Back in 2010 it was a four-wheel-drive, four-motor prototype that was destined for 1000-car per year production. It was set to receive distinct styling, its own spaceframe, a unique interior, a 1600kg kerb weight and due to be sold at “above R8” prices.

Now it’s a two-motor, rear-wheel-drive, 1780kg coupé prototype that’s based on the facelifted R8. Audi has developed and built 10 cars to a production standard, each valued at over £850,000, in a short space of time to demonstrate the technology and continue trials.

Opting for a rear-drive layout, instead of the quattro system found in normal R8s, may seem a somewhat counterintuitive move. Audi says, however, that the e-tron's rear-drive layout offers adequate traction, negating the need for four-wheel drive, and a more engaging driving experience. There would also be considerable packaging, weight and technical challenges to overcome using a quattro configuration.

The R8’s high-performance electric motors draw current from a 48.6kWh lithium-ion battery, the bulk of which sits behind the driver. Combined, the motors deliver 375.5bhp and 604.8lb ft. This allows the R8 e-tron to dispatch the 0-62mph sprint in 4.2sec and reach a limited top speed of 124.27mph. Derestricted it could reach over 155mph, at the cost of efficiency.

It’s not just the powertrain that’s different. The e-tron makes extensive use of carbonfibre, in order to bring its weight down to reasonable levels, and there are myriad cosmetic and technical changes. The braking system has undergone major revisions, while the motors allow for regenerative braking and an advanced form of torque vectoring.

One thing’s for sure: this is not a dull car. Press the start button and a bassy synthetic thrum fills the cabin. Select ‘D’ with the stubby gear lever, release the electronic handbrake and the R8 glides away.

Inside it's much like a conventional R8, barring instrumentation that shows power usage, levels and distribution. Snug bucket seats, which adjust only fore and aft, replace the standard items. The e-tron's steering wheel adjusts for rise and reach, however, so finding a comfortable driving position isn't too difficult.