2023 Porsche 718 vs 2024 Mercedes-Benz AMG GT

What's the difference?

The 718 Cayman GT4 RS is a street legal race car that offers outstanding performance while staying easy to drive. That said, if you plan to drive the car daily, be prepared for a less than comfortable experience.

Really, the GT4 RS is a car you can drive to the track and then home again, or for a country road blast, not something you could commute in daily.

Is it as good as a 911 GT3? The answer is no, but it’s not far off.   

This is no Lotus, but damn if it ain't a hell of a good time, and proof positive that electrification can enhance the V8 experience, rather than ruin it.

A Porsche with a fixed rear wing as big as an ironing board clamped in place by swan neck attachments should be enough to let people know they are in the presence of automotive greatness. 

If not, the bonnet with its NACA duct nostrils, the louvres cut into the wheel arches and the funnel-like air inlets where the back windows should be are also obvious signs this is no ordinary Cayman.

You and I know none of these features are just for the look. The GT4 RS is a Cayman redesigned for monster performance.

For starters the GT4 RS is 30mm lower and 35kg lighter than a regular Cayman.

Downforce is increased by 25 per cent thanks to that enormous fixed rear wing and front diffuser.

The NACA ducts in the bonnet pipe air down to cool brakes the size of family pizzas. Actually, at 408mm in diameter they're the same cast iron/aluminium discs you’ll find on a 911 GT3 and 28mm larger than the GT4’s. Also the same as a GT3’s are the rear 380mm discs.

Excess air pressure is released through the wheel arch louvres, while those giant ducts where back windows normally are feed the engine air like a baby prehistoric bird as it screams for more in your ear.

The GT4 RS only weighs 1415kg thanks to that carbon bonnet, a rear window made of light-weight glass, heavy insulation material has been taken out, the door handles inside are just fabric loops and even lightweight carpets have been used. 

The optional Weissach package is pretty much there for the look and gives the bonnet, rear wing and side air inlets the carbon weave finish. 

The pack also adds titanium exhaust tips styled to look like those from a 1970s Porsche 935 and inside it swaps the steel roll cage for a titanium version along with lots of leather and Race-Tex (synthetic suede) upholstery. 

The titanium roll cage is 16kg lighter than the steel version but it’s not FIA-GT approved.

The 20-inch forged magnesium wheels come with the Weissach pack and along with looking stunning they’re also 10kg lighter than the standard alloys.

It's a mean, but somehow still sleek, looking beast, this big AMG, but it's also immediately recognisable as a thing of intent.

Up front, there's the huge vertical-slat grille that looks like it drove straight out of a Stephen King novel, a massively domed bonnet, and these vacuum-like side intakes that look like they could suck in stray animals.

Then, at the back, there are twin dual-pipe exits (for four in total), and an automatic wing that pops out of the rear bodywork. And all of that's capped off with these massive 21-inch forged alloy wheels hiding golden ceramic-composite brakes.

Mean, yes, but not quite as aggressive as you might expect the most powerful AMG to date to come across, perhaps.

Inside, it's more subdued again, with the AMG presenting a pretty passenger-friendly space, with all the Benz tech you'd imagine, including the massive screens, and — thanks to its air suspension and drive modes — the ability to tailor the ride to your liking, meaning a comfortable and premium experience, despite the power under your right foot.

The 718 Cayman GT4 RS is a two seater sports car that’s probably more practical than you might think.

There’s a spacious cockpit with excellent legroom even for me at 191cm tall, plus good headroom. Those bucket seats were verging on snug for me at 90kg, but they weren’t at all uncomfortable.

Cabin storage is limited to a tiny centre console box only large enough for a wallet, while the door nets are good for phones. The glove box is large and lockable.

For luggage there are two boots: one in the front under the bonnet, and the other is in the back. Both will easily fit an airline carry-on sized suitcase.

It's not overly practical, given its size, with AMG locking in a four-seat configuration with a fixed rear pew that limits boot space. You can get folding seats, but only as part of an option package.

What you're left with is a vehicle that stretches 5054mm in length, 1953mm in width and 1447mm in height, but that serves up rear seating for only two – albeit very comfortably – and, because of the electric battery and motor being housed at the rear, boot space of just 335 litres.

There is triple-zone climate control, and the rear seating is lounge-like and luxurious, while the up-front space is ample for two full-size riders, too.

There's no spare, with AMG's 'Tirefit' puncture repair system on board.

There's no escaping the fact that a big number has been applied this AMG E Performance model in Australia, with the GT63S commanding $399,900, before on-road costs, and before you start selecting option packs.

Obviously performance is what you're really paying for here, but there are lots of niceties included, too.

They include an electric glass sunroof, 21-inch forged-alloy wheels with ceramic composite brakes, rear-axle steering, puddle lighting, power-closing doors (only sealing, not full hands-off closing), LED lighting, and an auto rear wing that retracts back into the body work at the rear.

Inside, there are twin 12.3-inch screens with Apple CarPlay and Android Auto, a Burmester sound system, Nappa leather seats front and back (which are heated and cooled in the front, and which offer a massage function), and three-zone climate control.

You can then spring for the 'AMG Night Package' ($3490) which adds the 'AMG Night Exterior Package', different 21-inch wheels in matt black, dark tints on the rear glass, black badging and dark chrome on the grille.

Then there's the considerably more expensive 'AMG Carbon Fibre Package' ($18,490), which gives you the carbon exterior package, carbon inserts in the side skirts, and more carbon on the front wing trim, the mirror housings, the rear wing (which is now fixed) and in the cabin.

There is more, of course, but we'll get to them under our performance, driving and safety sections.

The engine in the Cayman GT4 RS makes this car incredibly desirable and fast. It’s the 4.0-litre naturally aspirated flat-six from the Porsche 911 GT3. 

This isn’t a Cayman engine and it was never intended to be. Caymans come with turbo flat fours, and there is also a 4.0-litre flat six, but it’s not the same engine found in the 911 GT3 and the GT4 RS.  

So, how did it find its way into the Cayman? The story goes that Porsche’s head of R&D Wolfgang Hatz joked to his engineers that they should take the engine from a 911 GT3 and stuff it into a Cayman just to see what it’d be like. 

The thing is, once all the laughing stopped they actually attempted to do it. The job proved too difficult though, and Hatz told them to forget it. 

As it turned out it was only Hatz that forgot about it because the engineers continued to work on Cayman and even finished the job.

They revealed the Franken-Cayman to Hatz on his birthday and he was so besotted with the thing he pitched the idea of putting the monster into production. 

And now here I am reviewing the production version of the car - the 718 Cayman GT4 RS.

Unlike the 911 GT3 which has this engine at the rear of the car, the GT4, like all Caymans, is mid-engined. The driver and passenger are more or less leaning against the engine and the balance this creates is outstanding. 

Making 368kW and 450Nm the six-cylinder produces 59kW more than the GT4’s engine and revs to 9000rpm.

The howl from that engine as it storms up to that redline is one of the loudest I’ve heard from any production car. After a day of driving it on some amazing roads I came home and walked through the front door with my ears still ringing and the world’s biggest smile on my face.

Drive the GT4 RS calmly around, however, and it’s quiet. This is not a wake-the-neighbours-up-vehicle-when-you-start-it car. But if you were to arrive home at 8000rpm they’ll be awake by the time you’ve switched it off. 

Sending the drive to the rear wheels is a seven-speed 'PDK' dual-clutch automatic transmission. The ratios are super short, the shifts are lightning quick.

The GT4 RS doesn’t have a manual gearbox and there’s no plan by Porsche to offer one, either. Don’t let that put you off. PDKs can shift faster than you or me, and that’s what you want in a race car. 

That quick transmission is also part of the reason why acceleration is phenomenal with a 0-100km/h time of 3.4 seconds. A top speed of 315km/h makes the GT4 RS slightly faster than the 911 GT3.

It's not just what's under the bonnet, but what's at the rear axle, too.

But let's start at the front, shall we? Here, a familiar twin-turbo V8 engine lurks, producing a potent 470kW and 900Nm, which is fed through a nine-speed automatic, complete with paddle shifters and several drive modes, including the traction-limiting 'Race'.

But that is then joined at the rear by an electric motor with its own two-speed transmission, and which produces 70kW and 320Nm – or up to 150kW for 10-second blasts under heavy acceleration.

Combine both, and you're tapping into around 620kW and in excess of 1000Nm, enabling a sprint to 100km/h in just 2.9 seconds, and a flying top speed of 316km/h.

Porsche says that after a combination of open and urban roads the 718 Cayman GT4 RS will use 12.7L/100km. 

After leaving the city in peak hour traffic for flowing country roads, only to then join the commuters again on their way home, we measured 14.1L/100km at the fuel pump after 391km.

I’m not surprised by this mileage given I made no effort at all to conserve fuel, and compared to some of its supercar peers the fuel usage is darn good relative to what V8 and V10 sports cars tend to guzzle.

You'll need 64 litres of 98 RON premium unleaded to fill the tank, which translates to a range of just over 500km using Porsche's official consumption figure, and a tad more than 450km using our real-world number. 

Fuel efficiency is surprisingly impressive for a vehicle this big and powerful, with Mercedes claiming 7.7L/100km and 175g/km of CO2 on the combined cycle.

Helping that is a the 6.1kW battery, which delivers just 12km in all-electric driving range, but helps reduce overall fuel use.

This AMG is AC power only, meaning you can't recharge using fast chargers, but the brand says its secret trick is its ability to recharge itself using captured kinetic energy incredibly quickly – largely negating the need to plug in unless you want to unlock that EV range – with Merc suggesting that, on a race track for example, the battery will discharge and charge itself continuously as you're lapping.

That sleepless night before the day I drove the GT4 RS was worth every hour awake.

I’d planned a route which would take me on a round trip from Sydney’s inner suburbs to (in and around) the Blue Mountains to the west.

The automotive gods had given me a cool, dry and sunny day.  The only thing I didn’t have was a racetrack where a car like this can be set free and its abilities truly unlocked.

But I can tell you what it’s like to drive on great roads... and terrible ones.

First, the GT4 RS would be tough to drive daily on our Aussie city streets. Ground clearance is 103mm and higher speed bumps reach up and touch the undercarriage. 

This not only meant driving slowly over them, but at an angle. I was honked at for doing this.

Next, the ride is on the granite side of firm and the thin walls on the Pirelli P Zero tyres on our car (245/35 ZR 20 on the front and 295/30 ZR 20 on the rear) meant it fell hard into Sydney’s potholes. 

I wouldn’t call driving the GT4 RS in the city painful, but even on the most comfortable adaptive suspension setting it’s not all that pleasurable.

Those race seats aren’t the plushest place in the world, either, but I spent from pretty much 7:00am until 7:00pm pretty in mine and found it supportive and genuinely comfortable, while the driving position is excellent.

This is a low car, too, and if like me you’re over 45 and the height of a baby giraffe then be prepared to crawl in and out.

But it’s all worth it when the right road appears in front of you away from the traffic of the city.

That’s where you’ll glimpse the 718 Cayman GT4 RS's brilliance. It’s all here. Rapid acceleration accompanied by the sound of a tornado around you, but reined in by brutally effective brakes. 

Superb handling, balance and stability defy winding roads, while the nose is light and easy to point with the turn-in to corners committed and accurate.

The 718 Cayman is not just one of the best Porsches I’ve driven in the past decade but one of the best cars I’ve piloted in that time.

There's a lot of big numbers surrounding the Mercedes-AMG GT63S E Performance, but let me throw another one at you – 245km/h.

That was the high score I saw pop up on its digital speedo as the big and electrified Mercedes flew down the main straight at Sydney Motorsport Park (formerly Eastern Creek), before my courage ran out and my foot found the brake.

That kind of velocity is mind-bending in a vehicle this big, and so is the way that power is delivered, with the AMG's big brain deciding how and when to maximise power from the engine and electric motor to deliver a constant surge of torque that shoves you back, and the GT63S E Performance into the future.

But big acceleration is hardly surprising with that much power. What is a little more impressive is how easy this four-door supercar is to wrestle around a racetrack.

Sure, the feeling-out process is a little more involved, as you figure out how and when you'll feel the weight shifting, and as your brain struggles to compute how what's happening is even possible, but after a couple of laps the AMG settles into an easy, flowing rhythm that, while never feeling light on its feet, also doesn't feels like you're piloting a bus.

At least part of that is down to the wizardry on board, like the 'AMG Air Suspension', the rear-axle steering and the limited-slip diff, all of which combine to make the GT63S feel tighter and sharper than it would otherwise.

But it's also partly down to the prodigious power on offer – perfect corner entry and exits are less relevant when you have a cruise missile strapped to your right foot that doesn't just quickly make up for any driver errors, but shrinks the space between corners to the blink of an eye.

Yes, it's heavy, and there isn't much that's pure about the go-fast experience, but it left an ear-to-ear grin on my face, and isn't that priority one for any new AMG?

How does it drive on the road? That I don't know, as this was a track-only drive day. But we will get one on a proper test soon and let you know.

The GT63S E Performance is yet to be crash-tested (probably something about each one costing about the same as small apartment), but it does come pretty comprehensively loaded with safety kit.

That includes the standard 'Driving Assistance Package Plus', which delivers active cruise control, AEB, 'Active Steering Assist', 'Active Lane Change Assist' and nine airbags.

The Cayman GT4 RS is covered by a three-year/unlimited kilometre warranty and servicing is needed every 12 months or 20,000km.

With Porsche, final service costs are determined at the dealer level (in line with variable labour rates by state/territory).

We'd like to see the warranty coverage increased to five years/unlimited kilometres which will bring it in line with more mainstream brands.

A car like the GT4 RS is special, too, and likely to be owned for longer than just a few years and a longer warranty is good peace of mind.

The GT63S E Performance is covered by Mercedes' five-year, unlimited-kilometre warranty, and you can pre-pay your service costs to keep the prices down.

Service pricing for the electrified model is yet to be confirmed.