Kia K4 vs Mazda MX-5

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.

Ultimately, the design and tech changes to the ND MX-5 will be the biggest day-to-day advantages of the updated model, because the mechanical changes don’t make themselves hugely obvious on the road.

If you’re into track days, it’s still a satisfying car to hustle as fast as you can, but it’s at its most accessible on winding roads for weekend drives, where the new differential and track DSC mode won’t come into play as much.

But in a world where accessible sports cars are becoming a rarity, there’s only one rear-drive convertible with a sticker price appropriate for financial mortals, and it’s a pretty damn good thing that it’s the ND MX-5.

Note: CarsGuide attended this event as a guest of the manufacturer, with travel, accommodation and meals provided.

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. 

Alright, we’ve all seen ND MX-5s, you don’t need me to tell you about its proportions or explain its design elements to you in too much detail, so I’ll give you the headline changes.

At the front and rear are new pairs of LED head- and tail-lights, respectively… obviously, fitting into the spaces the old ones took up.

The DRLS and reverse lights have come off the bumpers for both, and are now part of the main lights at each end - no more DRLs in the front bumper, and the reverse lights have been replaced by reflectors.

There are new 17-inch wheel designs for the base and GT trim levels, too, and there’s a new colour - Aero Grey.

Inside, it’s a shame that the tan Nappa leather interior of the RF Black Roof can’t be had in a manual roadster, because it’s gorgeous, even though the inside still looks refined enough for a simple sports car in its base cloth trim.

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.

One thing Mazda has significantly changed for the ND is the multimedia screen, now a larger 8.8-inch touchscreen running Mazda’s updated software.

It brings the MX-5 up to date without sacrificing simplicity and makes it a little easier to use. The physical dial and buttons for controlling the screen also remain. The USB-C ports are also new.

Oh, and the MX-5 is the first Mazda model to get Connected Services, which is coming to other Mazda models eventually.

Connected Services allows owners to find, lock, and get alerts for their cars from a phone app, even letting them set curfews to notify them if the car is started during certain hours.

Aside from that, another small tweak is the simplified instrument cluster, which aims to be easier to read even when the roof is open and the sun is bright.

The cabin isn’t built to be plush, it’s built for ‘Jinba Ittai’, Mazda’s philosophy that applies most strongly to the MX-5 which means ‘horse and rider as one’.

And trust me, you feel one with the horse- er, car, when there’s not ample room to move. It’s not restrictive, but it’s cosy. 

Everything’s quite well-placed and it’s not busy with buttons or features in here though, it’s made for focusing on driving. 

One downside is the lack of storage, not even a glovebox, in front of the passenger, and the central storage spot under where your elbow sits is tiny, good for keeping the key fob snug though. Also, the cupholders are able to be removed or swapped between the space behind your elbow, or above the passenger footwell.

There’s also a small storage space between the seats behind where your elbow would sit, though it’s tricky to access while you’re driving.

Then there’s the boot, which is usable for a small amount of luggage at 130 litres in the Roadster and 127L in the RF hardtop.

Finally, as a huge positive, probably the biggest advantage of the ND over any other convertible is how easy it is to open and close the roof in the Roadster. You can do it single-handed, which is great if it starts raining and you’re at a traffic light or able to quickly pull over.

The RF hard-top has a switch that automatically opens and closes the roof section.

Getting into an MX-5 is now a little more expensive, with the base manual Roadster up by $2310 to now start from $41,520 before on-roads.

The top-spec soft-top GT RS is now $51,640, or $2800 more than before.

Pricing for the RF hard top is also similarly bumped up, a base manual costing $46,250, and the most expensive GT RS at $56,140.

There’s also a Black Roof edition which comes with tan Nappa leather inside, but that’s only available in an automatic RF, which is possibly the biggest downside to the 2024 range.

Base models get cloth seats, while GT and GT RS models get heated leather seats. The GT RS also comes with stiffer Bilstein dampers, Brembo front brakes, a bracing strut between the front suspension towers and a DSC-Track mode. The difference there is noticeable, so it's worth the extra spend for the more keen driver.

The higher overall costs bring updated tech, a new 8.8-inch touchscreen and a new limited slip-diff in manual versions, plus tweaked mechanicals like improved acceleration response and lower steering rack friction.

But they do look a tiny bit different too.

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.

Up front, you get one option: a 2.0-litre naturally aspirated four-pot. It makes 135kW and 205Nm, and it’s a delightful little thing, driving the rear wheels only - as it should.

It used to be that the smaller 1.5-litre engine was the more revvy, keen option, rest its soul, but Mazda updated the 2.0-litre to be more eager (and deliver more power) at high revs and basically made the little 1.5-litre redundant.

Anyway, you can have it with a six-speed manual in any variant, or a six-speed automatic in GT guise if you find manual gearboxes difficult or a hassle.

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.

Mazda says the MX-5 uses 6.8L/100km as a manual Roadster, or 7.0L/100km with an automatic gearbox. Or, in the heavier RF 6.9L for a manual and 7.2L for auto.

Not great for a tiny car like this, but pretty good for a sports car!

It’s got a 45-litre fuel tank, takes premium 95 RON or higher, and while it should hypothetically be able to travel more than 600km with its on-paper claims, expect fuel use to sit closer to 8.0L/100km if you’re driving it anything like it deserves.

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).

It feels like every motoring journo under the sun (literally if the roof is off) owns or has owned an MX-5 of some sort.

And the first time you drive one, you might understand why. 

If you spend your days testing and driving a bunch of different cars that aim to be many things at once, it’s refreshing to drive something that aims to be one: fun.

That’s it, the MX-5 feels like it was built to be fun. Not for convenience, not for power, certainly not for the school run.

And fortunately its simplicity remains with this update. All Mazda has done to change the way it drives is attempt to improve the rear limited-slip differential and improve the steering a little by reducing friction in the rack, as well as improve throttle response.

Has any of that changed the way it feels to drive on-road? No, not massively, but the ND was already such a delight that Mazda could have kept this update to purely design and interior tech changes and it would have still been one of the best-value buys around in terms of fun.

The MX-5 still feels relatively softly sprung while still being a dynamic and communicative sports car that’s engaging to drive even at low speeds, and rewarding (or frustrating) to drive fast.

On tight, winding roads, the MX-5 is at home, its soft suspension keeps you humble with its shifting weight and its relatively meagre outputs keep your licence safe.

In fact, despite being slightly compromised as a daily drive, the MX-5 is still plenty of fun even in traffic, there’s something about the satisfying click as the shifter slips into gear, or the little rev matches heading back down through the cogs when approaching a red light.

The 2.0-litre four-pot is a keen unit, and the six-speed manual is light and easy to work with, plus its steering is light without sacrificing road surface feedback - that feedback can quickly turn into cabin noise on a coarse highway which could become a little irritating on a long trip.

But the MX-5 can still be plenty of fun on track, where you’re more likely to get the most out of its new limited-slip differential and Track DSC mode.

It’s equally frustrating and satisfying to hustle the MX-5 around the East Circuit at The Bend in South Australia, where the track is twisty, busy, and unforgiving. Get it wrong, and the MX-5 lurches or slides to let you know you’ve made an error. 

Get it right, however, and the little roadster glides through the corners, camber changes and even over apex kerbs smoothly and carrying impressive speed.

Plus, the electronic assistance won’t usually kick-in until you really need it, a welcome change from cars that are constantly trying to keep you from having fun behind the wheel.

The ND MX-5 actually scored five stars with ANCAP back in 2016, even though its score has now expired. It’s not obvious how well it would fare under newer, stricter tests, given the small car’s lack of advanced driver assistance - not that that’s a bad thing in the case of a sports car.

Still, for a two-seat convertible, the MX-5 has a decent list of kit to keep you safe including front and side airbags, alerts for driver attention, blind spots, lane departure and rear-cross traffic, parking sensors and a reversing camera, belt pretensioners and side-impact door beams and even automatic Smart City Brake Support.

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.

Mazda’s five-year, unlimited km warranty covers the MX-5, including five years of roadside assist.

Servicing costs are pre-set, with intervals every 12 months or 15,000km up to seven years or 105,000km. They cost between $447 and $638, averaging out at about $544 each.