Five years ago, a mid-size SUV being sold without a diesel engine would have been unthinkable. Even now, despite sales of new diesel-powered cars continuing to plummet, it still might seem like a risk. But Volvo – a manufacturer already committed to abandoning the fuel with newly-launched models – has now taken the plunge with the XC40, with no more diesel-engined versions being produced.
So, what’s filling the void? Well, there’s much excitement from Volvo about the Recharge plug-in hybrid variant, and anticipation about the new fully-electric version due to arrive early next year. But those not willing to go so far into electrification just yet might be intrigued by the two mild hybrid petrol engines which have also joined the range – the 250hp B5, and the 197hp B4 tested here. So, might these be a tempting alternative for previous diesel drivers?
The system deploys a 48V battery to support the engine, using kinetic energy recovered when the car decelerates. It assists the engine while accelerating, and also – when eco mode is chosen from the selectable drive modes – allows its revs to drop to idle when coasting. Volvo says that compared with the previous equivalent pure petrol T4 powertrain, the B4 saves around 7g/km of CO2 – a reasonable chunk – and just over one mile per gallon of fuel, which is rather less impressive.
Even though this is the less powerful of the two new mild hybrids, the B4’s performance is still ample – though you can hear the petrol engine working perhaps a bit harder than a diesel would have under acceleration, producing as it does 100nm less torque than the old D4 equivalent did.
Powertrain aside, the B4 is unchanged from previous XC40s, but since the model has been one of our favourite SUVs since it launched that’s no issue. The chassis still offers good body control and a comfortable ride, while the interior remains a stylish place to be, with distinctive touches like the ‘driftwood’ trim on our Inscription-grade test car.
It’s a good overall package – but from a company car cost point of view the new powertrain isn’t quite as impressive. It may be good when compared with the old pure petrol, but taken in isolation the B4’s figures are rather less rosy. Even though this is the more modest of the two new mild hybrids, its official CO2 emissions of 174g/km are still enough to place it in the top 37% BIK tax bracket. There is a caveat to this though, in that we’re testing the thirstier all-wheel drive version – there is a front-wheel drive option which drops the CO2 figure to 162g/km, meaning it falls into the 35% BIK band. The only further efficiency saving possible with the XC40 range would be to drop down to the petrol T2 and T3 engines that are still on sale, with manual gearboxes, but these only offer very marginal improvements and come with a lot less power.
In case you were wondering, the old D4 diesel in all-wheel drive form also sat in the top BIK band, thanks to the 4% BIK diesel surcharge. However, its official fuel economy figure was more than 7mpg better, so while the mild hybrid system helps the petrol engine to close the gap very slightly, it still can’t replicate the efficiency diesel drivers were used to – and that’s without having mentioned the old D3 diesel, which offered double digit savings on both mpg and CO2. It’s perhaps no wonder, therefore, that Volvo has reported surging fleet interest in the plug-in hybrid version of the XC40, since that model’s more committed approach to electrification offers the potential for far greater efficiency savings than the mild hybrids can provide.
