Mercedes-Benz SL63 vs BYD Sealion 5

What's the difference?

The new Mercedes-AMG SL63 4Matic+ is guaranteed to turn heads for decades to come. But there’s enormous design and engineering substance underpinning this car’s undoubted good looks. Stunning performance, superb dynamics and top-shelf safety make this a powerhouse GT to be reckoned with.

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

While the BYD Sealion 5 lacks the polish of some more established plug-in hybrids, it has a seriously compelling price advantage over some competitors. It makes a base-model Mitsubishi Eclipse Cross PHEV feel positively outdated and it’s $13,800 cheaper.

BYD's lack of ANCAP rating for the Sealion 5 and the uncertainty around it still being a new brand are downsides, even if BYD is quickly moving past the latter. But being the most affordable PHEV available while having this much showroom appeal is bound to work in the Sealion 5’s favour, just don’t expect a dynamic masterpiece once you’re out on the road.

Rather than a strict two-seater, this time around the SL adds the flexibility of ‘+2’ rear seating while the previous 'Vario’ folding hardtop has been binned, the new car returning to a traditional, electrically-folding and weight-saving (-21kg) soft top. 

Mercedes-Benz design chief Gorden Wagener started the new model’s development from a ‘clean sheet’ and Mercedes-AMG says “not a single component comes from the predecessor SL, or any other model such as the AMG GT Roadsters”. 

Always a subjective call, but I think this car’s proportions are just about perfect. The lengthy bonnet with its twin longitudinal ‘Power Domes’, raked windscreen and fat haunches create a wide stance and presence that’s almost impossible to ignore.

Aggression, as with the sinister headlights and 21-inch rims, is subtly combined with soft curves along the flanks and around the rear. Note the seamless door handles.

And it’s not all about aesthetics. Active aero has been integrated into the front apron and retractable rear spoiler. Plus the ‘Z-fold’ roof design does away with the need for a separate cover.

The interior is sub-zero cool with slick screens, an 11.9-inch display covering multimedia and a 12.3-inch unit for instrumentation ahead of the driver, being particular highlights.

Turbine-style air-vents at the leading edge of the split-level dash and alloy trim elements are a tip-of-the-hat to SLs past and the deft mix of large flat surfaces with complex curves oozes design confidence.

The BYD Sealion 5, from the outside, is inoffensive but also uninspiring. That’s likely not such a bad thing for a mid-size SUV – it’s rare you’re hearing someone talk about how beautiful the Mazda CX-5 or Toyota RAV4 is. 

Its quartet of colour palette options comes in on the safe side, too. Aurora White is standard, Atlantis Grey, Harbour Grey and Cosmos Black are cost-options.

Our test car is Atlantis Grey, which is interestingly quite blue. 

The relatively upright shape is a slight departure from the more ‘aquatic’ silhouettes of BYD’s line-up, but the front grille and light layout are decidedly in step with the brand’s oceanic design language. There’s a bit going on, you could say.

The slimline tail-lights are the rear, especially from a three-quarter angle to the side, look attractive and help break up the rear without looking messy.

The Sealion 5’s design is overall net-good, but it’s inside where the mid-sizer feels like you’re getting plenty for your dollar.

The seats, despite the leather fakery, feel like decent material, and the layout uses buttons and physical controls cleverly without feeling outdated.

In the context of a high-performance GT, practicality is pretty impressive.

At just over 4.7m long the SL is a sizeable machine and much of its lengthy (2700mm) wheelbase is devoted to making the driver and front passenger comfortable.

There’s plenty of space for that pairing and just enough storage to cope with the ‘things’ they’ll typically bring with them.

Door pockets offer enough room for a few odds and ends, although you’ll struggle with even a medium-size bottle unless you’re willing to lay it down horizontally along the top of the aperture.

A handy lidded bin between the front seats doubles as a centre armrest, there are two cupholders under a sliding lid in the centre console and the glove box is a decent size. 

Power and connectivity options run to four USB-C ports, a 12-volt socket and the wireless device charging pad.

Then there are the rear ‘+2’ seats, and Mercedes makes no bones about the fact they’re intended for occasional use only, even suggesting a 1.5m occupant height limit.

And there’s no doubt they offer a handy emergency seat or a fun kids’ zone. Just ask a Porsche 911 Carrera owner how much this kind of seating arrangement increases a sports car’s flexibility.

At 183cm I gave the back seat a crack, which meant sliding the front (passenger) seat way forward with the backrest close to upright. But I squeezed in, and there was just enough legroom for a person in front at the same time. 

With the roof in place there’s the added pleasure of cranking your head over to around 45 degrees. But it’s do-able! 

No storage, adjustable ventilation, or power back there. But that’s fair enough, especially given there are USBs available in the front centre storage box.

Boot volume is 240 litres with the roof up and 213 litres with it folded, which is enough for some light luggage, and not too shabby when you think a Toyota Corolla hatch offers up just 217 litres (with all seats up).

There’s a 12V socket in there, but don’t bother looking for a spare, in the event of a flat your only option is a repair/inflator kit.

To actually interact with the interior is, at times, another story. BYD’s tech interface is generally easy to manage, but could be simpler when it comes to navigating menus for the sake of driver distraction.

While larger text and buttons would be welcome, the multimedia system is easy to use when parked, and the functionality is impressive for the price point.

Winning more points for the Sealion 5, though, are the physical controls – buttons and the traditional gear selector – which make the cockpit much more intuitive while on the move.

Ergonomically, though, the adjustment between the steering wheel and driver’s seat could do with some work, as I found it difficult to find a truly comfortable driving position. This is coming from someone 178cm tall, a very normal height in Australia.

Better adjustability on the steering column would be helpful, as it’s something I’m not sure I’d ever get totally used to.

Visibility and physical space inside the Sealion 5 is impressive, though. The car is 4738mm long, 1869mm wide and 1710mm tall, and the roof and window lines don’t swoop too aggressively towards the rear.

There are low window shoulders even into the rear, so light isn’t at a premium, though under-leg support could be better on the pew.

It’s otherwise un-cramped. The 2712mm wheelbase means decent legroom for second-row folk, plus behind the 60/40 split-fold seats there’s 463 litres of space for luggage. That becomes 1410L with the seats folded.

There’s unfortunately no spare tyre, just a tyre repair kit.

The BYD Sealion 5 Essential kicks off from $33,990 before on-road costs, four big ones less than the Premium ($37,990). We’re focusing on the Essential today, but don’t think that means a shallow list of features.

As you’d expect from BYD if you’ve been paying attention to the Chinese brand in its emergent years, the Sealion 5 comes with more than $34K would normally get you – a 10.1-inch central multimedia touchscreen, an 8.8-inch driver display, synthetic leather upholstery, dual-zone climate, a six-speaker sound system, wireless Android Auto and Apple CarPlay, USB-A and -C ports front and rear, digital radio and keyless entry.

On the outside, LED headlights and tail-lights are the same for both variants.

Both also have 18-inch wheels, not unwelcome for the benefits of on-road comfort.

Consider that the most popular SUV in the country, the Toyota RAV4, costs at least $45,990 without the benefit of a plug-in drivetrain (yet) and comes with, on paper, a more sparse list of features.

The closest PHEV competitors are still more pricey, including the Geely Starray ($37,490) and Chery Tiggo 7 ($39,990), and arguably lack the brand power BYD has come to enjoy.

This new ‘4Matic’ all-wheel-drive SL63 features AMG’s (M177) 4.0-litre twin-turbo V8, superseding the previous rear-wheel-drive SL’s similarly configured 5.5-litre unit.

Hand built by one AMG technician from start to finish, it produces 430kW (around 580hp) from 5500-6500rpm and 800Nm across a broad plateau from 2500-5000rpm.

It’s something of a mechanical masterpiece, and the previous seven-speed auto transmission, driving the rear wheels only, has been replaced by a nine-speed dual-clutch auto (with wet multi-disc start-off clutch) sending drive to all four wheels via Merc’s ‘4Matic’ AWD system.

The Sealion 5’s front wheels are driven by a combined maximum of 156kW thanks to a 1.5-litre four-cylinder petrol engine (145kW/300Nm) and a permanent magnet synchronous motor (72kW/122Nm).

BYD claims a 0-100km/h sprint of 7.7 seconds for the Sealion 5 Essential, four tenths faster than the Premium despite only a 61kg difference in kerb weight.

Mercedes-AMG’s official fuel economy number for the SL63 on the combined (WLTP) cycle is 13.9L/100km, the 4.0-litre twin-turbo V8 emitting 319g/km of CO2 in the process.

On the roughly 300km launch program we covered urban, B-road and some freeway running, returning an (indicated) average of 17.5L/100km. And that reflects some enthusiastic driving along the way.

The fuel tank requires 70 litres of 98 RON premium unleaded to fill it which translates to a theoretical range of around 500km, dropping to 400km using our real-world number.

With a charged 12.9kWh lithium iron phosphate (LFP) battery and a full 52-litre (95 RON minimum) fuel tank, BYD reckons the Sealion 5 Essential can cover 1001km under NEDC testing, which is optimistic. It claims 71km can be done on EV power alone.

Not only due to the lenient nature of NEDC testing (WLTP is more common and usually results in lower ranges), but the reality is that once the battery is flat, the engine is doing a lot more work.

Charging is slow, limited to 3.3kW (AC only), which should take between 4 and 5 hours to charge from the lower end of the gauge for the battery size. Given most PHEV owners will do this overnight at home, that’s certainly not the end of the world.

Claimed consumption figures are 1.2L/100km with more than 25 per cent battery charge, or 4.5L/100km when it dips below that.

Realistically you could do sub-50km trips and use no fuel, or never plug your Sealion 5 in and see fuel consumption soar. In any case, anything close to 1001km in a single run is extremely unlikely.

I recall driving the AMG SL65 around the backroads of Tassie a few years ago and that twin-turbo V12 monster famously packed 1000Nm of torque, while this car ‘only’ has 800.

But there comes a point where enough is enough… and this is enough!

With maximum torque available from 2500-5000rpm and peak power (430kW) on call from 5500-6500rpm there’s always stupendous acceleration available with a squeeze of your right foot.

Claimed 0-100km/h time is supercar fast at 3.6 seconds, while top speed is a toupe-troubling 315 km/h. And that’s electronically limited!

A typically ferocious engine noise and howling exhaust note accompany rapid progress and shifts from the nine-speed dual-clutch transmission are quick and positive, not to mention especially enjoyable using the steering wheel-mounted paddles.

There are six ‘AMG Dynamic Select’ drive programs from Comfort through to Race, the latter including a Drift Mode, which we didn’t experiment with. Nor did we dip into the ‘AMG Track Pace’ system for circuit-focused mapping and timing

However, far from drifting, the grippy Michelin Pilot Sport 4S rubber (275/35 fr - 305/30 rr) plants the car securely with the all-wheel-drive system and electronic locking rear diff playing their part.

I found the perfect set-up was in the ‘Individual’ mode with the engine, transmission and steering in racier settings and the suspension in ‘Comfort’. The adaptive damping in this configuration mixes smooth ride compliance with sharp dynamic response.

The car’s aluminium space frame chassis is part of a body structure mixing aluminium, magnesium, fibre composites and various strength steels.

Torsional rigidity is claimed to have been improved by 18 per cent and despite the lack of a roof the SL feels tight and solid.

Suspension is by alloy double wishbones front and rear with adaptive damping and active hydraulic anti-roll stabilisation standard (so, no physical anti-roll bars).

At the same time the 4Matic AWD system is able to vary torque distribution up to 100 per cent to the front or rear axle depending on where drive can be put to best use.

The speed sensitive, variable ratio, electronically controlled steering is accurate and turns in beautifully with good road feel. No doubt assisted by electric rear steering able to adjust the angle of the rear tyres by up to 2.5 degrees.

All this adds up to a hugely impressive package that, despite its 1970kg kerb weight, feels agile, athletic and able to attack corners like an overgrown hot hatch, putting its power down with unwavering authority.   

While indecently fast the SL63 can also stop rapidly with the AMG high-performance braking system standard. 

Huge composite ventilated and cross-drilled discs (390mm fr - 360mm rr) are clamped by six-piston fixed alloy calipers at the front and single-piston units at the rear. They wash off speed calmly and consistently with perfect pedal feel.

Even at highway speeds, particularly with the windows up, normal conversation is easy with the roof down. But if you need to raise (or lower) it, the operation takes 15 seconds and is possible up to 60km/h. 

Under the heading of miscellaneous observations, the turning circle is a not insubstantial 12.8m, so beware in the car park.

A front axle lift function is a welcome standard feature, raising the car’s nose 30mm with the press of a button. And lift locations are stored in GPS data, so the car will subsequently remember to lift itself at the same place, even if you don’t! 

Heating and cooling for the front seats combined with the heated steering wheel and Air Scarf neck warming makes winter top-down driving a pleasure.

The digital instrument display is not only crystal clear, it can be changed through multiple configurations, including a tunnel-like graphic for engine revs as well as specific readouts for speed, g-force, the lot.

At the same time, the central media screen’s angle can be adjusted to better cope with reflections and the windscreen wiper system Merc calls ‘Magic Vision Control’ channels fluid along the wiper arms onto the rubbers, which isn’t new, but works spectacularly well here.  

You might expect a car at this price, regardless of its drivetrain, to be underwhelming from behind the wheel.

That, then, makes it even more pleasantly surprising that the BYD Sealion 5 is actually rather competent. Not massively exciting or dynamic, but certainly not a disappointment.

The Sealion 5 is, save for a couple of arguably minor annoyances, quite easy to get used to and drive.

Firstly, when making proper use of its electric power, the drivetrain provides enough shove for its intended use. It’s not overly powerful, but you won’t have trouble overtaking. It’s the same with most of the inputs, the steering is light but not completely numb – again about right for how the Sealion 5 will be driven.

Perhaps its biggest departure from expectations based on other cars from China is its suspension is on the stiffer side of things, but again it’s not unruly or too rugged. In fact, it does provide a better sense of control than many of its compatriots.

Again, the biggest issue with the Sealion 5 day-to-day is its driving position, the steering column adjustment isn’t up to scratch and there’s not really a perfectly comfortable seating position (I’m a very standard 178cm).

On long trips, you might also find the engine gets quite noisy once the battery power is gone as it works hard to pull the mid-size SUV along under acceleration.

Its driver-assist systems are, you might be pleased to hear, on the calmer side of things – BYD is getting better at calibrating its safety features and I didn’t find myself rushing to switch it all off as quickly as usual.

It can still be a bit too persistent in its lane-keeping, but it’s a big improvement on the way things were.

There’s no ANCAP rating for the Sealion 5, but the list of safety kit isn’t lacking on paper.

BYD lists seven airbags ,including full-length side-curtain bags and an important centre airbag, plus there’s a whole suite of tech that’s, as noted, better behaved than past driver-assist systems from BYD.

The Essential only misses out on a surround-view parking camera and front parking sensors, both arguably important safety features for parents, but the rest of the list is the same as the Premium including adaptive cruise control, lane-keep and lane departure assist, traffic sign recognition, blind-spot monitoring, rear cross-traffic alert with rear AEB (as well as front AEB, of course) and tyre pressure monitoring.

The SL63 4Matic+ will be covered by Mercedes-AMG’s five-year/unlimited km warranty, with roadside and accident assistance included for the duration, both of which are expected in this category. 

Maintenance intervals are 12 months/20,000km, and a fixed-price service plan lists an average of $1583 for each of the first three visits to the workshop. Not exactly small change, but not unheard of in this part of the market.

BYD has a six-year/150,000km warranty, which is probably more than you’d need in terms of distance but is behind many competitor brands’ timelines – seven to 10 years is becoming the norm, even if it’s conditional.

An eight-year/160,000km warranty covers the battery, which is about par for the industry.

Servicing for the first five proper services ranges from between $285 and $930, plus there's a free check-up six months into ownership and a total cost over the span of $2355 – an average of $471 per service.

BYD has just over 100 dealerships in Australia, so finding one for servicing shouldn’t be too challenging.