Kia K4 vs Kia Optima

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.

If you travel long distances, want a good amount of space and don’t want to pay big bucks for a new car, then yeah, maybe there is a reason sedans like this will hang around for a while longer.

Sure, the appeal of sedans mightn’t be as strong as it once was, but models like the Kia Optima prove they still have a reason to exist.

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. 

Cosmetic changes for the facelifted 2018 Kia Optima include new headlights and tail-lights with revised LED signatures (but still halogen lamps in the base model), and there are newly sculpted bumpers and new wheel designs across the two-model range. 

We had the base model Si, which doesn’t look as good as the GT model, because it has smaller wheels, the sporty body kit and misses out on the LED headlights, but the LED daytime running lights are still present.

The GT has a more aggressive look, and the side skirts, front spoiler and rear diffuser fit it better - there are dual exhausts, but not sporty quad exhaust tips.

In fact, this model is a bit like the old-man version of the Optima. No offence intended to old men, of course. The GT is just heaps sportier, and I reckon it’s considerably more attractive as a result. 

Still, the inherent sleek styling of the Optima remains - the chrome highlighting along the window line is a bit too sheeny for me, but the angles and stance of this model are quite gracious. I really dig the fact the top of the windscreen mirrors the ‘Tiger Nose’ grille shape.

I'm no exterior designer, but I liked the existing Optima more - it just looked a bit neater, even though it had a decent amount of bling with its Mercedes-like diamond-pattern grille, as opposed to the cheese grater look seen here.

There’s not quite as much bling inside the cabin of the Si, either, but it is still a well-designed space - just not as special as the premium package offering of the GT (which gets leather trim - not nappa leather, but still a quality cowhide finish, and more). Check out our interior photos to see if you agree - but size and interior dimensions of the Optima are hard to argue against.

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.

I really like the way Kia designs its cabins. Sure, there’s a lot of black in here, but there’s also a lot of thought put into the usability of the space.  

The high-mounted 7.0-inch infotainment and multimedia touch screen in the Si is simple to use, and for 2018 the Optima range gets Apple CarPlay and Android Auto - you couldn’t get that in the Optima up to this point. 

Also included are a reversing camera, USB input, Bluetooth phone and audio streaming and six speakers. The Si model misses out on sat nav - you’ll have to use the maps app on your phone. No DVD player either.

Storage is well thought out in here, with big bottle holders in the doors, a good sized pair of cup holders up front, and a nice little storage bin for your phone, wallet, keys and so on.

There’s a driver info screen with a digital speedo, and even on this base model you get a dual-zone climate control air conditioner. The updated Optima gets a new steering wheel, too.

Now, what about the back seat?

It may be considered a ‘mid-sized’ sedan, but there’s limo-like space. With the driver’s seat in my position (I’m about six feet tall) there was still heaps of rear legroom in the rear seat, with ample knee room, good foot room and decent shoulder space, too - three of me could slot across the back bench comfortably, which means kids will fit easily, too. There are three top-tether points and two ISOFIX points as well.

Kids and adults alike will be happy with the rear air vents back here, and there’s a flip down armrest with cupholders, too. Again, big bottle holders appear in the doors, and there are map pockets in the back seats.

What about boot space? With so many people choosing SUVs over sedans because they’re theoretically more practical, the Optima offers good food for thought - it has enough luggage capacity for a bunch of suitcases (510 litres VDA in size) and there’s a full-size alloy spare under the boot floor. If you need more, you could always invest in a roof rack setup?

Kia dropped prices for this updated and facelifted model range - and not by a small amount, either. So, what's the price? How much does it cost?

The Si model is the entry-grade of two models, and it comes in at the bottom of the price list at $33,290 plus on-road costs (rrp) - an $1100 drop over the previous version. The Si, then, is a value-focused sedan that you might consider if you’ve looked at a Toyota Camry Ascent, Hyundai Sonata Active, Mazda6 Sport or Subaru Liberty 2.5i.

The standard equipment list is pretty good - although there have been some deletions, because the price is down $1100. The rather good HID headlamps with washers have been dumped in favour of halogen projector lights (yeah, not even xenons), and the satellite navigation system (GPS) is gone.

But now the 7.0-inch media screen is capable of doing the Apple CarPlay iPhone connectivity and Android Auto phone mirroring thing, and that’ll serve most people’s purposes pretty well, but there is no digital DAB radio, and no CD player for the sound system. Other standard kit includes a digital driver info display with digital speedo, dual-zone climate control, cloth seat trim, auto-dimming rear-view mirror, a reversing camera, front and rear parking sensors, auto headlights and rain sensing wipers, and 17-inch alloy wheels (with a full-size spare). 

New equipment for the Si includes driver-fatigue monitoring and an active lane-keeping assistance system (in place of the old lane-departure-warning buzzer). 

If you want all the fruit you really need to fork out the extra cash for the GT, which lists at $43,290 plus on-roads (vs $33,290 for the Si). That is getting perilously close to Kia Stinger territory… but let's not get too far ahead of ourselves - this isn't a model comparison!

You get a fair bit more for your dough, but even the GT has seen a few deletions to help justify its $1200 price drop compared to the pre-facelift model, such as the front passenger seat being manually operated (previously electric), the cooling/ventilation of the front seats has been deleted, and the panoramic sunroof of the previous model is gone, too. And while it rides on 18-inch rims with a new design, the tyre-pressure-monitoring system has been removed.

It uses a new 8.0-inch media screen with extended smartphone connectivity and in-built sat nav (with 10 years of maps included and SUNA live traffic updates), and it also gains redesigned LED headlights but they lose the smart auto high-beam assistance of the old model. The tech doesn't go as far as to include Homelink garage door opening here in Australia, either.

Other standard kit in the GT includes leather seats, electric driver’s seat adjustment with memory settings, smart key (keyless entry) and push button start, a sports body kit, a harman/kardon audio system with 10 speakers and a subwoofer, wireless phone charging (Qi) but no Wi-Fi hotspot, rear sunshades (but no tinted windows), different interior trim finishes, a heated steering wheel, and a colour driver-information screen. 

The GT also gets the new lane assist system and driver-fatigue monitor, and the entire safety approach has been improved across the range. See the safety section below for more detail. 

There is no launch edition, nor is there a sports edition, but there is a decent array of colours (or colors, depending on where you're reading this) available - black, white, blue, red, grey and silver can be chosen, but not brown, purple or gold... if you wanted those. 

Accessories available across both trim levels include tailored floor mats, a dash mat and weathershields, among other items. 

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.

The Si model is powered by a 2.4-litre four-cylinder petrol engine, which has seen no changes to its specifications for this mid-life update.

Engine specs remain at 138kW of power at 6000rpm, while torque is rated at 241Nm at 4000rpm. It makes use of a six-speed automatic transmission only - there’s no manual transmission here, but you do get paddle shifters - and it's front wheel drive (the Optima isn't available with AWD, or as a 4x4, or in rear wheel drive - the latter is left to its bigger brother, the Stinger).

The GT gets a zestier drivetrain with more horsepower - it has a 2.0-litre turbo four-cylinder engine with 180kW/350Nm, which is much more desirable, but also louder than the Si’s 2.4. It also has a six-speed auto transmission, and is FWD. If you're into ratings and statistics, that 2.0-litre with a turbocharger is one of the perkier offerings for its engine size in the class.

There is no hybrid model available, despite a plug in hybrid petrol version (allowing you to run in EV mode) being sold in European markets. No diesel here, either, while other markets get a 1.7-litre turbo diesel. No LPG model here, or anywhere else, for that matter.

Towing capacity for Optima models is 750kg unbraked and 1700kg braked for the 2.4-litre, and 700kg/1400kg for the 2.0-litre turbo. Tow bar down-weight is capped at 80kg.

If you're concerned about engine problems, suspension problems, clutch and transmission issues, be sure to check out our Kia Optima problems page.

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.

Kia claims a very realistic fuel economy rating of 8.3 litres per 100 kilometres for the Si model, and we saw damn close to that consumption during our week of testing. On the highway it will sit at around 6.5L/100km, ensuring good mileage, while city driving will push usage above 12.0L/100km. Our overall average was 8.5L/100km, which is good. Use the eco mode, and you'll get a little better use.

The turbocharged GT model uses a little more, according to Kia’s 8.5L/100km combined average claim, but we guarantee you’ll actually use more than that because it’s more eager to please.

Fuel tank capacity is 70 litres - plenty of size for long distance drives.

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 Optima has some really good elements to the way it drives, but sadly  some less impressive bits as well.

Let’s start with the not-so-great stuff - the 2.4-litre engine in this Si model just isn’t as enjoyable as the turbo unit, and the fact that Kia still doesn’t offer a hybrid version here, despite doing so elsewhere, is a bit of a downer.

The drivetrain isn’t terrible - the six-speed auto is smart enough, and there’s usable power if you boot it. The two more sedate drive modes, 'Eco' and 'Comfort', mean the transmission will aim to save fuel and limit throttle response, with a bit more of a lazy feel to the drive experience. But in 'Sport' mode it is definitely more rewarding in terms of acceleration and performance, offering a bit more pep and urgency (we didn't do a 0-100 km/h speed test, but take our word for it); it undoubtedly at the cost of fuel consumption.

It’s just a bit of a shame Kia doesn’t offer the turbo in this spec, too. Fuel use for the Si model is better than the turbo, however, so it could be ideal for buyers who are more worried about the bottom line than design and a sportier drive.

The thing I like most about the Optima is its road manners - the steering and suspension have been tuned for local conditions, just like all Kia products, and it shows. 

The electric power steering is really well sorted, making for easy parking moves and good assuredness at higher speeds. And the turning circle is decent, too - 10.9m (so, the turning radius is 5.45m). 

Plus the ride comfort is really good. On the highway it coasts along with very little fuss, and around town it deals with lumps and bumps impressively. Sharp edges can upset things a tad, and mid-corner bumps can make it jitterbug a little bit, but not to a degree that would rule it out of contention if you want a mid-sized sedan.

It’s pretty quiet on the open road, too, and the adaptive cruise control makes long-distance driving a simple task. The GT does suffer a little bit more road noise, though.

The safety rating of the Optima remains at five stars, as it was when the car was tested in this generation in 2015.

The updated Optima carries over the safety features of the previous model including autonomous emergency braking and adaptive cruise control, while the lane-departure warning system is now supplemented with lane-keeping assistance, and there’s driver-fatigue monitoring added, too. There is no park assist / self parking system.

That’s in addition to a reverse camera, front and rear parking sensors, and all the systems you’d expect, like stability control, anti-lock brakes, hill-start assist and seatbelt reminders.

Airbag coverage for Optima models is six: dual front, front side and full-length curtain. And parents will be happy to learn there are three top-tether attachment points, and two ISOFIX anchors, too. 

If you've been wondering to yourself, "where is the Kia Optima built?"The answer is South Korea. 

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.

Kia remains a shining light in terms of its new-car-ownership promise, with a very strong seven-year/unlimited kilometre warranty. It makes a lot of sense if you plan to hang onto the car for a while. There's no extended warranty available, which is understandable.

That plan also includes a roadside-assist plan for the same seven-year period, provided you maintain your car with Kia Australia. So, given you get one year to start with, then you get an extra year of cover every time you go back to Kia to get your car serviced, you could end up with eight years of coverage. Nice!

Servicing is due every 12 months or 15,000km, with the first seven years covered by a capped-price-service cost / maintenance cost plan. The costs are: service one - $289; two - $466; three - $360; four - $559; five - $325; six - $599; seven - $345. That makes a total cost of $2943, which is competitive for its class. Keep your owners manual or logbook up to date, and your resale value should hold up better.

If you have concerns about common problems, issues, reliability ratings and durability, you should check out our Kia Optima problems page.