Last week BMW revealed the i3, the first car in its "i" brand of sustainable vehicles. While we enjoyed the look at BMW's $42K electric, the reveal really left us wondering when we'll see the sportier i8. As if in answer, BMW held an event at its Miramas test track in France, showing the latest prototype.

Like the production i3, the latest iteration of the i8 loses the glass doors of the concepts that preceded it. The doors continue to swing open toward the sky, however. Given that the rest of the body is cloaked in the usual camouflage, it's difficult to tell exactly what else has changed.

BMW's latest information concerns itself more with technology and performance than looks. The basic underpinnings of the squiggly-camo prototype remain the same as they were the last time we checked in with the i8, but the numbers are tweaked ever so slightly.

The rear-mounted 1.5-liter TwinPower Turbo 3-cylinder engine puts out 231 hp, a slight increase over the 220 hp we had last heard. That engine works through a 6-speed automatic transmission also mounted in the rear. Teaming with the 131-hp front electric unit and its two-stage automatic transmission, the combo offers both all-electric driving, for about 22 miles (35 km), and quick, sporty all-wheel driving. The system puts out up to 420 lb-ft (570 Nm) of torque.

Previously BMW had said that the engine and electric motors could push the aluminum-chassised, CFRP-bodied i8 to 62 mph (100 km/h) in under five seconds, and now it estimates that its capabilities will be a full half-second under five seconds at 4.5 seconds. It can travel at speeds up to 75 mph (120 km/h) on pure electric power and 155 mph (250 km/h, electronically limited) under pure gasoline power. Like the i3, the i8 has a low center of gravity and near-perfect 50:50 weight ratio. Its curb weight is 3,285 lb (1,490 kg). BMW explains that the car's variable front-rear power splitting creates lively cornering by sending more power to the rear at the start of the corner and returning to the normal split to shoot the car out of the corner.

Like other upcoming sports cars – the Porsche 918 comes to mind – the i8 is a two-sided beast. One side is in the aforementioned sporty driving, and the second is in using its plug-in hybrid technology for a greater purpose. Like the latest performance specs, BMW's latest fuel economy estimate is a little higher than past figures: 95 mpg US (less than 2.5 L/100 km), with CO2 emissions at less than 59 g/km. The lithium-ion battery will take about 3.5 hours to charge from a 120-volt source and 1.5 hours with a 220-volt input.

BMW says that the i8 will become the first mass-produced vehicle outfitted with chemically hardened glass, commonly called Gorilla Glass. More common in smartphone screens, the glass will offer superior acoustic properties while saving weight in the rear window.

We're sure BMW will have plenty more details when it shows the production i8 at next month's Frankfurt Motor Show. The car will go on sale next year.

Source: BMW