One in every four Kia models sold in Europe is a Sportage, so it's fair to say this Slovakian-built model is a vital car for the company. But there's no resting on any laurels for the brand's best seller because it's already time for a mid-life facelift of the fourth generation Sportage – a shape that only arrived in 2016.

Interior and exterior tweaks are of the spot-the-difference variety, but there are some significant updates to the equipment on offer and one or two welcome new powertrain options. Among the most interesting arrivals is mild-hybrid diesel, based on a 48-volt electrical system, as reviewed here.

The automotive industry as a whole is gearing up to adopt this voltage level, as a means to achieve some of the fuel-saving and emissions benefits of full hybridisation without all the cost, packaging and safety issues that otherwise arise. So is this Kia a slice of the future that's ahead of the curve?

Our quick take

The facelift and equipment improvements to the 2018 Sportage will ensure it remains competitive, while this Ecodynamics+ mild-hybrid 48V version manages to deliver a useful CO2 reduction for the most powerful diesel version, though it is isn't cheap.

With the facelift, prices across the range have gone up by about five per cent or so, though perhaps surprisingly there hasn't been an extra large jump for those cars that now have 48V technology.

High prices will of course limit the mild-hybrid's appeal, but we're sure to see this technology trickle down to more mainstream, affordable models over the coming years. Hopefully those future cars might feature better packaging, to preserve essential boot space for a spare wheel.

Right now it's a step in the right direction and a future nod to where things can go.

Kia Sportage 48V Mild-Hybrid - 3.5 / 5

48-volt advantages

Because it delivers four times the electrical "oomph" of a 12-volt system, the 48-volt upgrade allows engineers to build more efficient electric motors that are smaller for the same power output, or conversely more powerful within the same sizing constraints.

You'll notice these advantages whenever the mild hybrid Sportage starts up: the familiar strained cough and jerk of a 12-volt starter motor is absent, replaced with a slick transition between switched off and running, as the diesel engine is spun smoothly into life by the system's integrated starter-generator unit.

Starter-generator is just a fancy name for an electric motor, connected to the engine's crankshaft by a belt drive. On the move the motor can continue to feed in its power from time to time, assisting the engine and helping to save fuel and improve acceleration.

The hybrid gear is currently available only with Kia's 2.0-litre, four-cylinder diesel engine. It produces up to 182bhp and 400Nm of torque, so the 12kW (16bhp) boost offered by the motor isn't huge and can't last long – the 48-volt lithium-ion battery in the boot holds 0.44kWh of energy, which means the motor can run it flat in about two minutes.

Regenerative braking 

In practice, energy flows back and forth between battery and motor in waves, because whenever you ease off or slow down, the motor switches into generator mode, providing regenerative braking that turns some of the car's momentum back into electrical power, sent straight back to the battery. 

Prod at the wheel buttons and you can summon up an animated display, showing these electrical power flows on the 4.2-inch colour screen that nestles between the instrument dials, though whether you should be watching this kind of thing while driving is debatable.

The regenerative braking effect feels quite natural – there's no sensation of being flung forward if you step smartly off the throttle, which happens in some pure electric cars such as the BMW i3. Indeed the Kia's hybrid technology is entirely unobtrusive and substantially improves overall refinement as a result of its smooth stop-start action.

Fiscal benefits

The impact of mild hybridisation will be felt most keenly through the wallet, especially of company-car users. The EcoDynamics+ Sportage we tested, in GT-Line S trim, has a CO2 rating of 152g/km, whereas the same-spec all-wheel-drive 2.0-litre diesel on sale before hybridisation came in at 166g/km. The difference yields a three per cent saving in Benefit-in-Kind (BIK) taxation, which for this car translates to about £415 saved per year for a 40 per cent bracket taxpayer in the UK.

In isolation this looks appealing, though it's worth considering the broader picture. The mild hybrid Sportage in '4' trim starts at £32,545, while the top-of-the-line GT-Line S version tested starts at £34,545.

These prices throw the Kia against some very well sorted opposition. Volkswagen's Tiguan springs to mind, which can be acquired with a 190bhp 2.0 diesel engine, a 7-speed dual-clutch automatic gearbox and all-wheel-drive, in SE trim, from £32,545. And despite not boasting any 48V cleverness, the VW is rated a little lower in CO2 terms, at 149g/km, which lops another one per cent off the BIK tax bill.

In other respects the new 48-volt powertrain has neither worsened nor improved the prior Sportage's performance figures and adds only 22kg to its roughly 1.7-tonne heft. Kia says fuel economy should improve by about four per cent, which may be significant for drivers who cover a lot of miles.

Ups and downs

The most noticeable drawback for choosing the mild hybrid is a loss of boot space, including the ability to carry a spare wheel. The 48-volt battery is bolted to the base of the boot behind the rear seats, under a lift-out floor, looking very much like a stuck-on afterthought.

Some of Kia's CO2 and fuel efficiency improvements will be down to a new 8-speed automatic gearbox. You can leave the transmission to its own devices, where it shifts up and down with reasonable intelligence and swiftness, or you can easily overrule it with paddles behind the steering wheel. 

As part of the overall range update, mild hybrid editions of the Sportage gain a 360-degree Around View Monitor, supplementing the reversing camera fitted as standard across the rest of the range. This feature creates a bird's eye view, showing obstacles around the car, and appears automatically when reverse is selected. It can also be summoned by pressing the 'view' button near the gear lever.

Camera views can be handy off-road, given that the mild-hybrid Sportage is offered only as an all-wheel-drive car. Other buttons on the centre console activate a Downhill Brake Control function, which limits speed on slippery slopes, and a transmission lock that sends 50 per cent of torque to the rear axle at up to 25mph, on mud or snow. On Tarmac, the Sportage is generally 100 per cent front-wheel-drive, though up to 40 per cent of engine output can make its way to the rear tyres when conditions deteriorate.

Welcome updates

Inside, a new 8-inch touchscreen embedded in the dashboard provides crisp, admirably simple graphics and features a TomTom satnav system, while Android Auto and Apple CarPlay are supported.

Adaptive cruise control and emergency braking systems are fitted to this hybrid, while the instrument display provides speed limit reminders gleaned through road-sign recognition. An upgraded JBL audio system with eight speakers is also fitted to the hybrid. 

Handily, the Sportage provides power sockets for both front and rear passengers, letting everyone keep their personal gadgets topped up.

Externally, the car's facelift brings restyled full-LED adaptive headlamps, as well as eye-catching chrome slats linking the front fog lamps to the lower grille. Both the fog lamps and daytime running lights feature a distinctive quad-cube design. All versions with the 48V powertrain come with 19-inch wheels and silver mock skid plates in the front and rear bumpers.

To recap

The addition of 48V mild hybrid technology brings a small but worthwhile improvement to the Kia Sportage SUV in CO2 and fuel efficiency terms, though the results are not spectacular and outright figures remain worse than some key rivals. But it's a step in the right direction.