We hit the road in new electric BMW 5 Series

THE importance of the i5 to BMW is as great as any car the brand has launched in a long time. The 5 Series is an iconic nameplate - BMW has shifted more than 10 million units in seven generations - and the i5, which is arriving alongside combustion-engined variants of the new 5 Series, is arguably the biggest step ever for the range.

- Sean Carson

But BMW is well placed to capitalise on the growing market for premium EVs, having exploited this with its pricey, polarising ix SUV, luxury i7 limo and sleek, sporty four-door i4. There's the all-new iX1 at the more affordable end of the market, too.

The i5 takes familiar technology and evolves it. It's based on BMW's CLAR platform, with the firm's fifth-generation eDrive motors fed by a battery that's "less than 90kWh", we're told.

We're here to assess if the Mercedes EQE and Tesla Model S have something to worry about once the i5 is on sale, and the answer is a resounding "yes". The BMW delivers the balance between comfort and sportiness every 5 Series has, but the car's ability has been widened, to offer more of both.

Of course, the numbers are as important to an EV as how the car feels to drive - and from what we can ascertain (BMW is still keeping powertrain specifics a close secret), the i5 should be right on the pace.

Two models will be available from launch - a rear-wheel-drive eDrive40 and a dual-motor, all-wheel-drive M60 xDrive - both powered by the same battery. The 335bhp 40 can achieve a maximum range of 362 miles, while this drops to 320 miles for the 590bhp M60. Expect maximum charging of "around 200kW", so a 10 to 80 per cent charge should take less than 30 minutes.

The 40 feels fast enough (expect 0-62mph in around six seconds). This rear-drive prototype's instant punch pushes it forward in superb refinement. It's a simple and relaxing car to drive swiftly.