Mercedes-Benz SL-Class vs Porsche 718

What's the difference?

The SL's overall score is somewhat skewed by everyday concerns, and rules are rules - an average punter will find the price of this car somewhat confusing and the devil-may-care attitude to fuel consumption bewildering.

If neither of these things are a problem, then the SL63 makes plenty of - well, not sense, because it's not a particularly clever or considered car - but it fills a niche that not so long ago we all thought would go the way of the dodo.

The fact it sells so few examples is betrayed by some of the cabin amenities and the fact that Mercedes hasn't put much effort into reducing the car's weight to improve its consumption or sharpen up the handling.

The fact it still exists at all is pretty damn cool, though, and for certain people an SL63 purchase is the culmination of a lot of hard work.

If it is your dream car, the SL63 won't disappoint. Everyone who rode with me said it was mightily impressive, but you've got to really want it. When you're not far off buying a Ferrari California T or Aston Martin V12 Vantage S for the money, you'll need a real yearning for the three-pointed star to go this way. And if you do, good luck to you - you've probably worked quite hard to get here.

If this is to be the end of the 718 as we know it, then it is an end to be remembered. Porsche has produced something special in the Spyder RS, a sports car that can compete with the 911 on any stretch of road - which is something so few cars can claim. The focus on performance has driven the entire concept of the car, but all the elements work in harmony, with form and function coming together.

The SL has always been completely unapologetic about its size and seems to be designed to accentuate rather than hide its length and width. The long bonnet screams power and prestige, and get out of my way, and is reminiscent of the little-loved McLaren SLR project of some years ago.

The size of the Mercedes logo on the huge front grille leaves you in little doubt about the brand of car that’s about to pass you at speed and some might say (okay, I would) that its large surface area is a little vulgar.

Like the SLR, the design doesn't seem to have a particularly cohesive strategy, with a number of Mercedes elements from around the traps that climb over each other. Roof up it looks awkward because of the gigantic posterior while with the roof down it looks overly long and, again, tail-heavy.

Folding hardtops are notoriously cumbersome and need a lot of room to hide them, but the silent operation is something to behold.

Elements that are worth deleting if possible are the dodgy 'Biturbo' badges. It's that kind of bling that gets people raising their little finger at you.

As the pinnacle of not only the current 718 range, but potentially the entire combustion engine era of the Boxster, Porsche has pulled out all the stops for the Spyder RS.

This includes major changes to the design, but none are purely for aesthetic reasons and instead are driven by the search for performance; and the fact they make the 718 look tougher, meaner and more purposeful than ever before is just a bonus.

It’s a comprehensive redesign that starts at the bumper with a new front lip spoiler to enhance downforce. Then there’s a pair of NACA ducts on the lightweight bonnet to improve brake cooling without compromising aerodynamic drag. The lightweight front fenders include wheel arch vents to stop any potential for front-end lift at high speeds.

And the fenders aren’t the only component that’s gone on a diet, there’s a lighter exhaust, lighter wheels, lighter bonnet, lighter roof, lighter door panels and even lighter carpets on the inside. All up, the Spyder RS tips the scales at 1400kg, which is 40kg lighter than a standard 718 Boxster.

If it’s still not light enough, you can opt for the optional 'Weissach Package' (which was fitted to our test car), which brings even lighter 20-inch forged magnesium wheels and carbon-fibre reinforced plastic for a range of parts including the front luggage compartment, rollover bars and ducktail spoiler on the Gurney flap – plus some cosmetic enhancements.

And we still haven’t even touched on the biggest design change yet - the rear half of the car. Starting with the roof, which Porsche actually calls a ‘sunshield’ and ‘weather guard’ because it’s a stripped down version of what the brand usually uses, to save weight and let the glorious engine noise into the cabin uninterrupted.

But it’s also necessary because the entire rear engine cover has been redesigned to accommodate the larger engine that Porsche has installed in the Spyder RS, a 4.0-litre six-cylinder instead of the usual turbocharged four-cylinder ‘boxer’ engines.

While the Spyder RS looks great with the roof/sunshield on or off, frankly the removal process is much too complicated and requires repeated viewings of a YouTube tutorial to still get it wrong.

While owners will (likely) eventually get the hang of it, it will always be a clunky and awkward process and that’s just the price of being so focused on performance, which you can accept or not.

Inside that ethos of performance over practicality continues, with sports seats, an Alcantara-wrapped steering wheel and even the previously mentioned lightweight carpet floor mats.

It’s a purposeful, rather than luxurious, cabin, but that perfectly suits the nature of the Spyder RS. Our test drive included several long stretches behind the wheel and at no stage did it feel uncomfortable or impractical, despite its stripped-down design.

“Practicality” is about as relevant to this car as a code of ethics is to a drug dealer or a contract killer, because the SL63 buyer is hardly worried about cupholders and boot space. For what it's worth, there are four cupholders in the two-seater cabin (which might explain why owners aren't worried about their liquid carrying prospects) and a minimum boot space of 364 litres and a maximum - with roof up - of 504, which is actually not bad.

Cleverly, there's a little robot-operated luggage cover inside the deep boot that stops your gear from being crushed when the roof goes down.

There's also space in the long doors where you might secrete a bottle of wine that would get a NSW Premier fired if he thanks you for it, and a bin in the console to hide your phone.

One area where the 718 range is starting to show its age quite dramatically is the in-car technology. While Porsche’s native system is relatively user-friendly, the lack of wireless Apple CarPlay or Android Auto in any capacity is deeply out-dated; and was frustrating for this Android using reviewer.

Given the age of the current 718 platform, and the impending arrival of the new model, it’s understandable that the multimedia system didn’t get an overhaul, but for a $350K car it does feel a bit behind the times.

In practical terms the Spyder RS is a bit of a struggle if you plan to go away with it. We managed to get a small suitcase and backpack in the under bonnet storage, but that was at capacity. While the addition of the larger engine removes any meaningful rear storage space.

The bad news is, the Spyder RS costs just over $200,000 more than the entry-level 718 Boxster, which is not a small sum of money. The good news is, for that $200K, Porsche has overhauled the 718 from nose-to-tail and enhanced it in nearly every aspect.

There’s a raft of mechanical changes that we’ll get to later on, to help justify the $334,200, plus on-road costs, asking price, but from a specification perspective there are some notable inclusions. 

For starters it comes with the 'Porsche Communication Management' (PCM) multimedia system, which includes in-built navigation and Bluetooth connectivity, as well as a 110-watt sound system.

But Australian delivered cars get an even higher level of standard equipment than other countries, with LED headlights including 'Porsche Dynamic Light System' (PDLS), cruise control, digital radio, rear 'ParkAssist' with reversing camera, 'Light Design Package', tyre fit set and windscreen with grey top tint, plus a no-cost optional Bose Surround Sound System all included.

It may be $200K more than 718 but compared to a 911, it actually makes a pretty compelling value argument. A 911 Cabriolet Carrera S starts at $342,700 (plus on-road costs), making that Spyder RS $8500 cheaper and a genuine alternative to its ‘big brother’.

Then, when you compare it against similar mid-engine European sports cars, such as the Maserati MC20 (from $510,000) or McLaren Artura (from $477,310) the Porsche looks like a bargain; relatively speaking, of course.

The SL63 is powered by Mercedes’ increasingly famous V8, with two turbos along for the ride to add oomph and cut the car's famous consumption, at least slightly. The 5.5-litre unit produces a massive 430kW and a scarcely believable 900Nm of torque.

All of that heads rearward via a seven-speed dual-clutch transmission that helps sling the 4.6m, 1848kg machine to 100km/h in 4.1 seconds.

The key stat for the engine is the cylinder count. Gone are the four cylinders and instead it’s a return to Porsche’s iconic flat-six.

Specifically, the same 4.0-litre six that Porsche uses in its 911 GT3, which is a lot of engine to squeeze into the middle of this lightened sports convertible.

In order to keep the 718 in its place (beneath the 911), Porsche has slightly detuned the engine, so it makes 368kW/450Nm (compared to 375kW/460Nm in the 911 GT3), but the German brand has never worried about a kilowatt contest and instead prefers to focus on driveability and the other elements that make a drive great.

To that end the combination of air-intakes next to the headrests and the lightweight stainless steel exhaust (which gets titanium tips on the Weissach Package) helps the Spyder RS sound like a Carrera Cup racing car when you really wind it up to its 9000rpm redline.

Not that the performance isn’t spectacular, though, with Porsche claiming it takes the Spyder RS just 3.4 seconds to run 0-100km/h, only 10.9 seconds to get from 0-200km/h and will hit a top speed of 308km/h.

The engine is paired to a seven-speed dual-clutch auto transmission (or PDK in Porsche-speak) that the company claims has “short-ratios”, but with peak power not hitting until 8400rpm and peak torque from 6750rpm, you don’t have to rush the ratio changes.

Much as is the case with the price, there's no real way to soften the blow here - the SL63 drinks like a footballer on Mad Monday, except it does it every day. The official combined cycle figure of 10.2L/100km is quite easy to double, as we did, averaging 21L/100km in mostly flowing suburban traffic. In the car’s defence, the accelerator pedal spent a good deal of time near the firewall.

The SL does have stop-start to help reduce its considerable environmental impact.

Porsche says the 4.0-litre engine in the Spyder RS uses 13.0L/100km, which is a big number for what is a relatively small car. But that engine is highly-tuned and built for performance not efficiency, so it’s something owners will need to accept.

Our test drive included some long highway stretches, as well as some spirited driving and urban commuting, so a good mix across all conditions, and we saw consistent returns around the 15-16L/100km range.

It has a 64-litre tank, which means a theoretical driving range of around 490km, assuming you can hit the official claim.

There are a number of impressive things about the way the SL drives. Firstly, astronauts will be familiar with the galactic thrust of the V8. It seems endless, seamless and ready to sling the big coupe into the outer atmosphere. Few engines of any kind can match the relentless go on offer in the SL and much of the credit should go to the seven-speed twin-clutch transmission.

When you jump on the brakes and shift down, the exhaust keeps the show going with angry crackles and pops.

Containing a torque figure like the twin-turbo V8's requires a lot of electro-trickery to stop you from being launched off the road. The great thing about all that stuff is that it works unobtrusively and smoothly.

Mashing the carpet in an SL without traction control would create much sound and smoke but little forward progress, such is the twist on tap. The SL has a range of modes from full-nanny (which is meant to keep you on the slippery Alpine road you've chosen to get you to some Swiss ski resort) while turning the dial all the way around to Race loosens the bonds.

It's in this mode you'll have the most fun and it does seem that the intermediate settings are a bit of a waste of time. Race mode does little to diminish the amazing ride quality provided by the active suspension setup, but relaxes the reins on the huge rear tyres. Exiting roundabouts is suddenly a huge laugh, with the tail cheerfully breaking traction and the two-mode exhaust thundering in a most pleasant way.

Better still is that when you jump on the brakes and shift down, the exhaust keeps the show going with angry crackles and pops, with more on the way when you lift off. There's little to match the aural pleasures of a properly tuned V8 and Mercedes has resisted the temptation to quieten it down on the outside and generate a fake noise for the inside. Although that would be stupid in a convertible, if you think about it.

The SL63, despite its AMG badge, isn't about all-out handling, of course. The Ferrari California would definitely show it how it’s done on a winding country road. The SL is more about flow, building momentum and rarely shifting down to second gear. The monstrous torque is enough to keep things rolling but should you wish for a bit more of the exhaust bellow, second is there for the taking.

Hustling the big convertible feels wrong, not because it can't do it, but because it's not really what it's for. Having said that, it offers a kind of fun that nothing else on Earth will provide, not even a Bentley GTC.

With the roof up, the SL63 is a quiet place but not remarkably so. The huge sticky tyres do the cabin's hush no favours, with an annoying roar on a wider range of surfaces than you might expect.

Roof down, it's hardly a paragon of virtue. A lot of wind noise reaches the cabin, even well below the huge speeds the SL can reach. So if you want to talk, it's windows up you'll need to deploy the mesh screen that bridges the roll hoops.

I’m only giving it a nine out of 10 because perfection is hard for any car to achieve, but the 718 Spyder RS goes as close as any car I’ve driven. This is a masterpiece of modern sports car design, pushing the 718 closer to the 911 than ever before, which is something Porsche has clearly tried to avoid so as to not tarnish the image of its flagship.

But with the 911’s 4.0-litre flat-six in the middle of the 718, plus its more compact dimensions, the lightweight nature of the Spyder RS and the raft of chassis and handling enhancements, this really does leave you questioning ‘do I really need a 911?’

The steering is fantastically direct, the chassis responds to every input with precision and feedback and the braking is strong and consistent. Which helps because that engine is so good it launches you with ferocity and a glorious noise (as good as anything on the market today) whenever you squeeze down on the accelerator.

The highest praise I can give the Spyder RS is not that it was a dream to drive on winding, challenging roads, but that it was just as enjoyable on a trip to the shops or cruising down the freeway. Any drive in this car is a genuine pleasure.

This is another area where the 718 is showing its vintage, with very little in the way of active safety features. There’s the required stability control, as well as airbags for driver and passenger, plus the previously mentioned reversing camera. But that’s it, there’s no autonomous emergency braking, no lane-keeping assist or even adaptive cruise control.

While that may sound shocking to some, there’s never a moment where you feel unsafe in the 718. It feels incredibly stable and responsive on the road, as the onus falls back upon the driver to pay attention and make smart choices.

There’s no ANCAP rating for the 718, or any Porsche, so it is a question of putting your faith into Porsche’s in-house safety measures.

The SL63 is covered by Mercedes' three-year/unlimited kilometre warranty. And, er, that's it.

It’s difficult to give the Spyder RS a clear score here because Porsche is cagey on the details. The public dealer websites indicate annual oil maintenance is required, with additional servicing every two years or 15,000km. 

How much that will cost is unclear, as despite the rest of the 718 range having publicly available prices, there were no such details for the Spyder RS (or even its Cayman sibling, the GT4 RS).

For reference, the 'standard' 718 requires oil maintenance ($895) for the first annual service and an inspection ($1500) the year after. Those costs continue to alternate annually out to eight years/120,000km.