Kia K4 vs Lexus Rx450H+

What's the difference?

The new Kia K4 GT-Line has a lot to offer - an interesting design, lots of features and a pleasant driving experience. It’s not without its quirks and there are times when a more powerful engine may have improved it for me as a long-term prospect as I do some big kays every year but it ticks the boxes as a friendly urban dweller.

The new Lexus RX450h+ Sports Luxury is packed with a wealth of premium features and strikes a solid balance between refinement and practicality. There are enough thoughtful touches that make everyday driving a little easier.

You’ll get the most out of the plug-in hybrid powertrain if you’re able to charge it regularly; ideally every day. That might not always be practical for busy people on the go, but overall, the RX450h+ manages to blend efficiency with Lexus’ signature comfort and quality.

Have to admit I wasn’t convinced on the design of this new sedan at first as it can look a little out of sorts from certain angles. But the more time I spend with it, the more I appreciate its sharp lines and sporty rear shaping.

The small sedan market doesn't have a lot of options now because SUVs are so popular but it's nice to see a design that stands out and the fang-like LED light design at the front and rear, as well as the 18-inch alloy wheels make the K4 look very cool.

The rear doors look sleek because the handle has been hidden in the C-pillar and the K4 is particularly striking in our test model's 'Wave Blue' ($600 RRP) paint colour.

Head inside and you'll find a cabin that looks slick with a two-tone synthetic leather upholstery that feels supple underhand and a plethora of soft touchpoints under all the bits that touch.

The black headliner creates a posh space but the sunroof helps the cabin to feel airy when you need it to.

The dashboard isn't too wide, preferring a sharply linear shape and is headlined by a massive display panel that houses dual 12.3-inch screens and a 5.0-inch climate panel.

There is still a strong presence of plastics inside but you don’t tend to focus on them.

Unlike some other new cars hitting our market, the K4 hasn’t done away with its buttons and dials - and there’s enough to satisfy those who don’t like to rely on a screen for everything. The extra traditional element of the physical gear selector adds to its charm as well. 

The RX isn’t breaking new ground with its plug-in hybrid design, but it still delivers that signature Lexus understated refinement.

The strong, flowing body lines, 21-inch alloy wheels and updated 'spindle grille' all give it presence without screaming for attention.

And in a segment where boxy and bulky designs tend to dominate, the RX’s swoopy silhouette helps it stand apart in all the right ways.

Inside, the cabin feels considered and luxurious. There's a heavy use of premium materials, including the leather and suede upholstery, plush soft-touch surfaces and the big, crisp displays that make the space feel modern and high-end.

The panoramic sunroof brings in loads of natural light, too, which is especially welcome given the dark headliner that might otherwise feel a little heavy.

If I have one gripe, it’s the thin steering wheel, which doesn’t quite match the otherwise solid, tactile feel of the rest of the interior. But overall, the cabin is a space that feels luxurious and well-executed. It's quietly confident, just like the RX.

The K4 feels big for the class, especially compared to its nearest rivals and that translates to a cabin that feels adult-friendly in both rows. An impressive feat for a small sedan.

Access is the only time you will have moments of 'I should have opted for an SUV'. That's because you will get in your daily squats sliding in and out of the K4 due to its 140mm ground clearance.

The rear doors also feature a wide wing that juts out from the door handle and it catches your hip almost every time you go to close the door.

The wide front seats offer lots of comfort with thick padding and long under-thigh-support. The driver's side is powered with adjustable lumbar support but the passenger seat only offers manual adjustments, which is surprising for a top-grade model. However, both front seats enjoy heat and ventilation functions.

The back bench seat offers similar comfort to the front with seat padding and length but it's not terribly wide and two adults (or child car seats) will fit best.

Amenities and storage is decent for the class with each row enjoying four drink holders and two USB-C ports. Front rowers also get a wireless charging pad and 12-volt socket.

In the front there is a large glove box that fits more than just an owner's manual, a mid-size middle console and a centre console that features retractable cupholders to open up the space if you need to. A dedicated phone cradle with small spaces on each side rounds up individual storage for the front.

In the rear there are two map pockets, a small item cubby next to the USB-C ports and a pair of directional air vents, reading lights and a fold-down armrest.

The boot space is massive for the class at 508L (that's nearing mid-size SUV territory) but the aperture is narrow and I couldn't fit my big booster seat through the opening.

The boot is quite deep as well and you may find yourself climbing into it to retrieve items that roll into the back.

The rear bench seat has a 60/40 split which can help with storage and there is a temporary spare tyre underneath the floor.

While you don't get a powered tailgate in this model, the lid isn't heavy to operate and has a proximity opening function that keeps it practical when you have your hands full.

This just means when you approach and stay near the boot with the key fob on your person the boot lid will pop open for you.

The 12.3-inch touchscreen multimedia system looks great with crisp graphics and a responsive touchscreen. The menus are in an easy-to-understand layout which you'll get accustomed to in no time. The 5.0-inch climate display sits to the right of this system and it's nice to have it on display all the time.

The 12.3-inch digital instrument cluster isn't all that customisable but it's easy to read with large text and a small menu screen that shows nav directions, trip info or a compass.

The built-in satellite navigation system is easy to get going and to cancel a route guidance, it's a one button affair which is great for when you're on the go.

The system features wired and wireless Apple CarPlay and Android Auto. The CarPlay is simple to connect to and retained a steady connection this week with feedback from my callers that my voice was clear on calls.

The RX cabin is thoughtfully laid out and impressively practical, with a premium feel that doesn’t come at the cost of everyday usability.

Up front, there’s plenty of space for driver and passenger, yet the stepped dash design brings a sense of intimacy. The electric front seats are seriously comfortable, with four-way lumbar support and extra adjustment functions that make this an easy choice for long drives.

Storage options are generous, too. There’s a clever dual-opening centre console, large glove box, multiple phone-sized shelves, map pockets and a couple of cup- and drink holders in each row.

Charging is taken care of by four USB-C ports, one USB-A port and a wireless charging pad.

Tech is up-to-date and well-integrated. The upgraded 14-inch media display looks crisp, supports wireless Apple CarPlay and Android Auto, and is paired with a revamped 12.3-inch digital instrument cluster and a colour head-up display.

The cluster’s new layout is modern and much easier to read than the previous offering. The digital rear view mirror also earns its keep when the cabin’s packed with passengers or gear.

One of my favourite touches? The seat controls on the side of the front passenger seat. It makes quick work of moving the seat forward, especially helpful when you’ve got a kid clambering in with a school bag full of projects.

Access to the rear row is easy, but the stadium-style seating, where you're perched noticeably higher than those in the front, won’t be for everyone.

That said, the rear seats are plush and padded, though they lack side bolsters, which rear passengers might notice during cornering.

Legroom is generous and the hardened kickplates are a dream to clean when your child’s treating the seatbacks like a climbing wall.

My eight-year old gives the back seat a glowing review, thanks to its creature comforts, including rear climate control, directional air vents, seat heating/ventilation on the outboard seats, two USB-C ports and retractable sun-blinds, which are a crowd favourite in our household.

There are three top-tether anchor points, and the bench is wide enough to fit three child seats, though bulky booster seats might be tricky due to the raised seating height.

At the back, the boot is well set up for families, offering electrically folding rear seats, a 12-volt socket, flat loading floor, and a hands-free powered tailgate.

Under the floor, there’s a small compartment for your charging cables (Lexus throws in two!) and a usable 612L of capacity when all seats are in use. One downside, though, is the lack of a spare tyre as you just get a tyre repair/inflation kit.

There are four variants in the RX range, and we’re testing the 450h+ Sports Luxury AWD, which sits just below the flagship and packs in plenty of premium kit for its $123,500, before on-road costs, price tag.

That makes it slightly more affordable than its main PHEV rivals; the BMW X5 xDrive50e (from $125,885 MSRP) and the Volvo XC90 Ultra (from $124,466 MSRP).

The Volvo does offer seven seats to the Lexus’ five, which may matter for larger families, and both rivals also outdo the RX on electric-only driving range - 65km in the RX compared with 77km in the Volvo XC90 and a generous 101km in the BMW X5.

Still, the RX fights back with a seriously stacked features list. Highlights include a panoramic sunroof, 10-way powered front seats with heating and ventilation, electrically folding rear seats (also heated and ventilated in the outboard positions), and a heated, power-adjustable steering wheel. Sound is taken care of by a premium 21-speaker Mark Levinson surround system.

Technology has had a solid upgrade with the 14-inch touchscreen multimedia display, 12.3-inch digital instrument cluster, digital rearview mirror, colour head-up display, live traffic navigation, wireless Apple CarPlay and Android Auto, 4G connectivity, four USB-C ports, one USB-A port and a fast wireless charging pad.

There’s also access to the 'Lexus Connected Services' app, allowing you to remotely lock or unlock the vehicle, pre-set the cabin temperature via three-zone climate control, configure driver profiles and even use your phone as a digital key.

Practical features include keyless entry and start, rain-sensing wipers, dusk-sensing LED headlights, rear sun-blinds, intelligent seatbelt reminders for the first two rows, a child presence alert and a hands-free powered tailgate. However, due to the plug-in hybrid system there’s no spare tyre, just a tyre repair kit.

The flagship grade is front-wheel drive and has a 1.6-litre four-cylinder, turbo-petrol engine that produces up to 142kW of power and 265Nm of torque giving this a more powerful presence than its non-turbo siblings (which only produce up to 112kW/192Nm).

However, while the power is adequate for the GT-Line there are times when the engine sounds like it's working a bit too hard.

The eight-speed torque-converter automatic transmission can also become flustered as it moves through the lower gears, especially when you’re accelerating quickly.

On the whole, the power delivery and outputs are more than enough for a city environment and the odd road trip.

Under the bonnet the RX450h+ Sports Luxury runs a plug-in hybrid powertrain that pairs a 2.5-litre four-cylinder petrol engine with a CVT auto and dual electric motors - one on each axle. Together, they produce a total of 227kW of power, though Lexus doesn’t quote a combined torque figure.

Still, it’s quick off the mark for a large SUV, with a 0-100km/h time of 6.5 seconds. There’s more than enough grunt for daily driving and overtaking, even if it doesn’t quite match the outright power of its key PHEV rivals.

With an official combined (urban/extra-urban) cycle fuel usage figure of 6.7L/100km and a fuel tank size of 47L, this model has a theoretical driving range of 701km. That does sit around 80 kays less than some of its rivals but it’s still sufficient for those wanting to do the odd road trip!

My on-test fuel usage has popped out at 9.2L/100km, which is based on figures achieved at the pump (32.05L) and my km travelled (348km).

I’ve done mostly urban trips this week with one longer open-road drive and overall I’m not too surprised by that figure because I’ve been pushing it hard but it could be better.

The K4 is a simple gal because Kia recommends a minimum 91 RON unleaded petrol to be used for all models.

The plug-in hybrid system brings solid efficiency, with claimed fuel use of just 1.3L/100km. In real-world conditions (mostly urban driving with regular recharging) I managed a respectable 4.8L/100km, which makes a strong case for the hybrid set-up.

The fuel tank holds 55 litres and it's worth noting Lexus recommends using a minimum of 95 RON unleaded petrol to fill it.

Using our real-world economy figure you can expect a range in excess of 1100km between fills.

The RX450h+ is fitted with a relatively small 18.1kWh lithium-ion battery, supporting an NEDC electric-only range of up to 65km.

While that’s fine for short daily trips, it’s shorter than you'd ideally want in a family SUV of this size and it lags behind rivals like the BMW X5 and Volvo XC90 in this department.

Charging is simple enough. The RX uses a Type 2 charging port and accepts up to 7.0kW on AC power, which means a full charge takes around 7.5 hours, perfect for overnight top-ups. Lexus also includes an at-home charging cable and second adapter cable as standard, which is a thoughtful touch.

As mentioned earlier, the power is adequate to move this car around on the open-road but you have to be a little aggressive on hills to keep your speed consistent.

It’s not always quick off the mark, though, and you’ll notice that when you have to cross traffic or enter a roundabout - so allow for extra car lengths. Once you get going, it’s responsive in the city.

The steering is sports-stiff and so is the suspension. This makes the handling feel nimble in turns and sure-footed when doing quick lane changes but you hear and feel every bump in the road. 

On-road comfort is okay around the city but the road noise is very loud inside the cabin and is particularly noticeable at higher speeds. You’ll have to raise your voice to chat to passengers in the back when you're on the highway.

The K4 has a small turning circle of just 10.7m and you can easily do a U-turn in spaces that others might have to do a three-pointer. This made the K4 feel friendly in small car parks and on ramps.

The direct steering makes it easy-enough to park, as does the reversing camera and front/rear parking sensors but I’m pretty disappointed that at the top grade-level, you miss out on a 360-degree camera system (tsk, tsk, Kia).

The RX450h+ delivers power that’s pert and prompt, with genuine bursts of acceleration that make driving fun. It’s always ready to go and there's no lag in stop-start traffic - which gives it a lively, dynamic feel around town.

The transition between petrol and electric power is seamless; you hardly notice the switch, which makes for a smooth, refined driving experience. The cabin is impressively quiet, even on the highway, making long trips comfortable and peaceful.

Regenerative braking isn’t adjustable and is subtle enough that many won’t notice it which is likely a plus for fans of traditional internal combustion engines who are making the PHEV leap.

The adaptive variable suspension adds a sporty edge to handling, letting you confidently take corners at speed. There’s some body roll but the RX never feels top-heavy or unsettled.

The steering carries the weight of the SUV but remains well-balanced and responsive. Overall, it’s a well-tuned machine that’s a pleasure to drive.

Maneuverability is a strong suit, too, thanks to a tight 11.8-metre turning circle and a clear, easy-to-use 360-degree camera system. Parking is easy-as-pie, which a lot of drivers will appreciate.

The RX earned a maximum five-star ANCAP safety rating in 2022, scoring highly across all protection categories: 90 per cent for adult protection, 89 per cent for child protection, 89 per cent for vulnerable road users, and 93 per cent for safety assist systems.

Standard safety gear includes eight airbags (dual front, front side, curtains, front centre, and driver’s knee) plus a comprehensive suite of driver aids. Standout features include emergency call functionality, child detection alert, side exit assist, front and rear collision warnings, park assist and emergency steering assist.

Additional tech covers blind-spot monitoring, driver attention monitoring, tyre pressure monitoring, daytime running lights, LED cornering lights, rear cross-traffic alert, lane departure alert, lane keeping assist, traffic sign recognition, and intelligent seatbelt warnings for the front two rows.

Visibility and parking are enhanced by a 360-degree camera system and front/rear parking sensors, while adaptive cruise control adds comfort on longer drives.

The rear seats have two ISOFIX mounts plus three top tether anchors, accommodating child seats safely. Autonomous emergency braking is active from 5.0 to 80km/h for pedestrians, cyclists, and backover and up to 180 km/h for cars.

The K4 GT-Line is offered with Kia’s seven-year/unlimited-kilometre warranty. That’s a pretty good term for the class and there is a seven-year capped price servicing program for a flat $3877 (averaging $554 per service), which is slightly more expensive than others in the class.

Servicing intervals could get annoying if you do big kays every year as they're spaced at every 12 months or 10,000km, whichever occurs first.

The RX comes with a five-year, unlimited-kilometre warranty, which matches its key rivals but isn’t exactly class-leading by today’s standards.

Servicing is handled via a capped-price program, with each service costing $695. The intervals are well spaced at every 12 months or 15,000km, whichever comes first.

This Sports Luxury grade also includes a three-year complimentary 'Lexus Encore' membership, granting access to a handy phone app and member benefits at partners like Westfield and Ampol. On top of that, you get 24/7 roadside assistance for added peace of mind.