Kia Optima vs Mercedes-Benz CLS-Class

What's the difference?

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.

Comfortable when it needs to be and sporty when you want it to be, the CLS 53 is a bit like Mercedes’ Doctor Jekyll and Mr Hyde – or maybe Bruce Banner and the Hulk is a better frame of reference for some.

While it doesn’t excel in any one particular area, its breadth of useability is commendable, but ultimately it might be its all-too-familiar aesthetics that is the biggest letdown.

From the inside, it looks and feels like any other large Mercedes model (not necessarily a criticism), while the exterior – in my opinion – doesn’t go far enough to differentiate it from the CLA.

After all, if you wanted a stylish and sporty sedan, shouldn’t feel special too?

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.

Mercedes’ homogenised design is a bit of a double-edged sword, and while the CLS does wear its styling confidently, it probably looks a little too much like the cheaper and much smaller CLA for our tastes.

Both are swoopy four-door coupes from Mercedes-Benz, so of course there will be some similarities, but keen-eyed car spotters will notice some differences.

While the proportions are similar, the longer wheelbase and bonnet line gives the CLS a more mature look, and the extra details found in the head- and tail-lights, and front bumper stand it apart.

The changes to the 2022 version also brings in AMG’s 'Panamericana' front grille, which adds a bit of welcome aggression to the front end.

From the side, the steeply raked roof flows seamlessly into the rear, while the 20-inch wheels fill out the arches well.

All four doors are also frameless, which is always cool to see.

From the rear, quad-exhaust tips hint at the CLS’s sporty intentions, while a prominent rear diffuser and subtle boot lid spoiler also feature.

Inside, the biggest change to the CLS is now the inclusion of the MBUX multimedia system, which keeps it in line with the E-Class, C-Class and other Mercedes models.

AMG sports seats are also fitted, wrapped in Nappa leather and 'Dinamica' fabric upholstery for all pews.

Our test car also came fitted with red contrast stitching and seat belts, adding a racy streak to the CLS cabin.

Have to point out the new steering wheel that comes with the 2022 CLS, though, which mirrors the tiller offered in the new E-Class, and is a step back in terms of functionality.

It looks premium enough thanks to its chunky leather-wrapped rim and gloss black dual-spoke design, but using the buttons, especially when on the move, is difficult and unergonomic.

This design is definitely function over form, and might need a few more revisions to get it right.

Overall, we’d say the CLS is a good-looking car, but does play it a bit too safe with its styling?

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?

Measuring 4994mm long, 1896mm wide, 1425mm tall and with a 2939mm wheelbase, the CLS slots neatly between the E-Class and S-Class in size and positioning.

Up front, occupants are afforded ample room for head, legs and shoulders, while the electronically adjustable seats make it easy to find a comfortable position.

The steering wheel also features a telescoping function – an always appreciated feature – and the expansive glasshouse makes things feel open and airy.

Storage options include a deep door pocket, a cubby found under the armrest, two cupholders and a smartphone tray with wireless charging capabilities.

It’s a different story in the second row, though, as the sloping roofline does noticeably eat away at headroom.

Don’t get me wrong, a six-foot-tall (183cm) adult can still slide in there fine, but the roof is dangerously close to the touching the top of the head.

Leg- and shoulder-room is pretty good in the outboard seats though, while the middle position is compromised by the intrusive transmission tunnel.

In the second row, passengers have access to a bottle holder in the door, a fold-down armrest with cupholders, backseat map pockets and two air vents.

Opening the boot reveals a cavity offering 490 litres of volume, with an aperture wide enough to fit golf clubs or luggage for a weekend getaway for four adults.

The rear seats also fold in a 40/20/40 split fashion, but Mercedes-Benz is yet to detail how much volume is on offer with the rear seats down. And as a traditional sedan, the CLS is less practical than the liftback Audi S7.

When the third-generation Mercedes-Benz CLS-Class hit Australian showrooms in 2018, it was available in three flavours, but the 2022 refresh has trimmed the line-up to just one – the top-spec AMG-tuned CLS 53.

The discontinuation of the entry-level CLS350 and mid-tier CLS450 means the CLS-Class now kicks off at $188,977, before on-road costs, which makes it more expensive than rivals like the Audi S7 ($162,500) and Maserati Ghibli S GranSport ($175,000).

With BMW ditching the 6 Series, the Bavarian brand doesn’t offer a direct rival to the Mercedes-AMG CLS 53, but its bigger 8 Series is offered in a Gran Coupe body style that starts at $179,900.

So, what does Mercedes include in the CLS’s asking price?

Standard equipment includes interior ambient lighting, a head-up display, 12.3-inch digital instrument cluster, power-adjustable and heated front seats, woodgrain interior trim, powered boot lid, rear privacy glass, push-button start, keyless entry, and a sunroof.

As an AMG model, the 2022 CLS is also fitted with a unique steering wheel, sports seats, illuminated door sills, drive mode selector, 20-inch wheels, a performance exhaust, boot lid spoiler and blacked-out exterior package.

Handling multimedia duties is a 12.3-inch 'MBUX' (Mercedes-Benz User Experience) touchscreen, with functions including Apple CarPlay/Android Auto connectivity, digital radio, a wireless charger, satellite navigation and a 13-speaker Burmester sound system.

It’s a long and fully-featured equipment list, for sure, and it’s so extensive that there aren’t really any options available.

Buyers can opt for an 'AMG Exterior Carbon Fibre Package', power-closing doors, and different finishes for the exterior paint, interior trim and seat upholstery – that’s it!

While its nice that everything you’d want comes included in the asking price, it’s hard to ignore the fact that its Audi S7 rival is more than $20,000 cheaper, but also well equipped.

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.

Powering the Mercedes-AMG CLS 53 is a 3.0-litre turbocharged inline six-cylinder engine, punching out 320kW/520Nm to all four wheels via a nine-speed automatic transmission and Merc's '4Matic+' AWD system.

A 48-volt mild-hybrid system, known as 'EQ Boost', is also fitted that serves up to 16kW/250Nm from take-off.

The result is a 0-100km/h acceleration time of 4.5 seconds, keeping it on pace with the likes of the 331kW/600Nm Audi S7 (4.6s) and 390kW/750Nm 250kW/500Nm BMW 840i Gran Coupe (5.2s).

While not as brutish as AMG’s eight-cylinder engine, the straight six strikes a great balance between pace and poise that perfectly suits a model like the CLS 53.

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.

Official fuel consumption numbers for the CLS 53 are pegged at 9.2 litres per 100km, while we managed an average of 12.0L/100km in our launch drive.

All of our driving was relegated to country back roads and high-trafficked urban areas however, with no consistent freeway driving.

We’ll reserve judgement on how accurate the fuel economy figures are until after we’ve had the car for longer, but the EQ Boost system is designed to help keep consumption down by being able to coast the engine in particular situations.

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.

There are certain expectations on a vehicle when it wears a Mercedes badge, namely it should be comfortable to drive while also dripping with the latest tech. And here the large four-door coupe delivers in spades.

Driving the car is smooth, easy and comfortable when in its default drive setting, you can really sink into the CLS and just eat up the miles in comfort.

There are small niggles, like the 20-inch wheels and low-profile tyres (245/35 front and 275/30 rear) throw up a bit too much road noise into the cabin, but for the most part, around town, the CLS is serene, supple and supremely soothing.

However, switch it over to Sport or Sport+ and the steering gets a bit heavier, the throttle response a bit sharper, and the suspension a bit stiffer.

Does it transform the CLS into a sports car? Not quite, but it certainly dials up driving engagement to a level where you can really have some fun.

Though this isn’t a full-fat AMG in the same vein as an E63 S and doesn’t feature the ubiquitous 4.0-litre twin-turbo V8, the CLS 53’s 3.0-litre six-cylinder engine is still plenty potent.

Coming away off the line feels particularly brisk, likely due to the EQ Boost system adding a bit of poke, and even flat-footing it mid-corner delivers a noticeable surge of urgency from the creamy straight six.

However, the best of the CLS 53 experience, in my opinion, is actually the sound, with the exhaust letting off the right sort of pops and crackles in Sport+ mode on overrun.

It’s rude and obnoxious, but also completely surprising coming from the motoring equivalent of a three-piece dress suit – and I love it!

The brakes are also up to task for scrubbing speed, but our relatively brief time with the car was in extremely wet conditions, so the 4Matic+ AWD system was hugely appreciated.

The Mercedes-Benz CLS is yet to be tested by ANCAP or Euro NCAP, which means there is no official crash-test rating that applies to local market vehicles.

However, the standard safety equipment list is extensive, and covers autonomous emergency braking (AEB), nine airbags, rear cross-traffic alert, blind-spot monitoring, tyre pressure monitoring, a surround-view camera, route-based speed recognition and lane-change assist.

The rear seats also feature two ISOFIX mounting points for child seats.

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.

Like all new Mercedes-Benz models sold in 2021, the CLS 53 comes with a five-year/unlimited kilometre warranty with roadside assist over that period.

This outclasses the assurance period offered by BMW, Porsche and Audi (three-year/unlimited kilometre), and matches that available from Jaguar, Genesis and Lexus, who recently upgraded their offering.

Scheduled service intervals are every 12 months or 25,000km, whichever occurs first.

The first three planned services will set buyers back $3150, broken down as $700, $1100 and $1350 apiece.