Tesla and Volvo, for instance, fit heat pumps as standard to some models but they are expensive components. Polestar, for example, charges £900 for a climate pack including a heat pump. But the cost will fall as production ramps up.
Vehicle weight and battery regeneration
Weight contributes to tyre and brake losses, especially during city driving, but overall it has a smaller influence on energy consumption in an EV than in an ICE car, since energy is harvested during brake regeneration.
Greenwood says designers expect about 2% energy reduction for every 100kg saved in highway driving, while in city driving, where braking and regen are more common, the contribution of a 100kg saving is more like 5%.
Tyres and brakes
At motorway speed, tyre friction and drag between brake discs and pads draw around 12% of the battery’s power. But at city speeds, tyres and brakes replace aero as the biggest loss, reaching up to 50%.
So low-rolling-resistance tyres (such Michelin Pilot Sport EVs) are essential. Brake drag is being addressed with active management of the clearance between the pad and disc.
Lights and wipers
“We’re talking about reducing the power consumption of headlamps, windscreen wipers, blower fan, indicators and brake lamps,” says Greenwood.
Switching to an LED bulb in brake lights, for example, can save 1% in efficiency, particularly in stop-start traffic.
Marginal gains and test cycle
Jon Hall, head of research at Mahle Powertrain, emphasises that hitting 5.0mpkWh will depend on a series of marginal gains.
“It’s all about the reduction in parasitic losses, nibbling away at a lot of efficiency improvements and marginal gains,” he says.
But Mahle cautions that real-world efficiency can differ considerably from figures in the WLTP test. Air-conditioning systems, for example, are switched off in the test.