BMW has launched its 'i' sub-brand with two brand new models - the i3 and the i8. The i8 has been designed as a 2+2 coupe: as fast as an M3; more economical than even the best hatchbacks. It will use a four-wheel drive system with its plug-in hybrid engine.
The main engine will be a 1.5 litre petrol engine with direct injection that develops 220bhp and 221lb ft of torque. This will be twinned with the 129bhp, 184lb ft electric engine to produce 349bhp and 491lb ft of torque overall. The car will run on its electric power alone or a combination of the petrol engine and the electric engine based on the state of charge and driving conditions.
The car will be traditionally BMW in that it will use a rear-wheel drive system, but the engine will mounted in the rear, connected to a dual-clutch gearbox. Where the petrol engine powers the rear wheels, the electric engine will be mounted more traditionally in the front of the car, powering the front wheels using a twin-speed transmission.
To give the car its incredible efficiency, BMW has ensured that the motors work very intelligently. In stop/start traffic situations the car will run entirely on its electric motor - pick up speed, or deplete the battery and the petrol engine will engage, enabling four-wheel drive and much more performance.
And this performance? 0-62mph in 4.6 seconds. 50-75mph takes just 4 seconds flat and the car will easily reach its electronically limited top speed of 155mph. The car is not simply quick due to its power alone, though: it is fairly lightweight due to its carobfibre-reinforced plastic body at 1480kg, giving it a power-to-weight ration of 236bhp per tonne.
The electric motor, light weight and lack of aerodynamic drag thanks to its swoopy design give the very fast car very good economy. BMW claims the car will get 104mpg on a combined cycle and 66g/km, and that these figures could get even better in optimal running conditions and an even more improved car by the time the i8 goes on sale in 2013.
The biggest problem with electric motors has always been their recharge rate. However, if all goes to plan at BMW, the i8 will be fully recharged in just 105mins on a standard household socket - leaps and bounds ahead of any other hybird technology on the market.
The estimated range is around 400 miles because the BMW uses a start/stop system along with a multi-stage brake recuperation system.
It should handle well too, as the i8will come with double-wishbone front and multi-link rear suspension in a car with 50:50 weight distribution and a lower centre of gravity than any other BMW model.
In size it is most comparable to the 3-Series coupe at 4623mm in length, 1955mm in width and 1280mm in height, and with a convertible planned, will the faster and much more economical i8 be a shot in the arm for BMW or the first car in an entirely new sector?
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