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Bodystyle, dimensions and technical details

For now, the i4 comes in two flavours. We’re testing the more powerful, dual-motored M50 derivative, which makes 537bhp and 586lb ft from its two synchronous motors (one per axle) and in doing so eclipses the BMW M3 Competition in terms of outright clout. The entry-level i4 eDrive40 puts out 335bhp and 317lb ft solely through the rear axle, though both cars are fitted with the same 83.9kWh in-house battery pack, which is some 20% more energy- dense than the one in the BMW i3.

Fifth-generation eDrive technology means the maximum charging speed is also the fastest BMW has ever achieved, at 205kW, though this is realised only at lower states of charge, the i4 rapid charging at closer to 100kW through the mid-range of battery capacity.

Underpinning the i4 is the same modular CLAR platform found underneath the 3 and 4 Series. In terms of footprint the two cars are closely aligned, the i4 being just 5mm longer in wheelbase and with marginally wider tracks. This much you can surmise simply by looking at the car, whose silhouette and general proportions resemble those of the 4 Series Gran Coupé.

Twenty-two bolts fix the battery pack into the floorpan, where it adds considerable torsional rigidity to the platform but also adds 550kg, which is why the i4 M50’s claimed 0-62mph time of 3.9sec trails the M3 Competition xDrive by almost half a second.

Both i4 models get additional bracing around the front struts, and there’s an extra aluminium shear panel below the subframe. Unique to the M50 is another new brace that connects the strut towers, though rather than being flaunted like the carbonfibre brace in the old F80-generation M3, it’s a simple aluminium shaft, hidden beneath undramatic black cladding.

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Aside from the battery pack, the only other major departure the i4 makes from the 3 Series recipe is to use air springs for the rear axle – that and the traction control system being integrated into the motor management, thereby eliminating long signal paths for the DSC and allowing the system to act up to 10 times faster than it would in a conventional ICE arrangement.