Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS
Compare the Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS. The Mercedes-AMG C 63 S Saloon is £30,000 cheaper. The Porsche 718 Cayman GT4 RS is 0.6s quicker to 60mph. The Mercedes-AMG C 63 S Saloon is more fuel efficient. Full performance, cost & ownership breakdown.
The Mercedes-AMG C 63 S Saloon is priced from £55,000, powered by a 4.0L Twin-Turbo V8, producing 503 hp, with 700 Nm of torque, reaching 0-62 mph in 4 s, a top speed of 180 mph, sent to the road via rear-wheel drive. The Porsche 718 Cayman GT4 RS is priced from £115,000, powered by a 4.0L Flat-6, producing 493 hp, with 450 Nm of torque, reaching 0-62 mph in 3.4 s, a top speed of 196 mph, sent to the road via rear-wheel drive.
The Mercedes-AMG C 63 S Saloon offers a 435-litre boot, folding rear seats, runs on petrol, returns around 26 mpg, is covered by a 3 years / unlimited miles (original UK new-car cover) warranty. The Porsche 718 Cayman GT4 RS offers a 125-litre boot, a usable front boot, runs on petrol, returns around 21.4 mpg (WLTP combined), is covered by a 3 years / unlimited miles (original UK new-car cover) warranty.
On cost of ownership, the Mercedes-AMG C 63 S Saloon is £30,000 cheaper than its rival, the Mercedes-AMG C 63 S Saloon costs less in annual maintenance (£1,100 versus £1,300), the Mercedes-AMG C 63 S Saloon is the more fuel-efficient choice.
Driving Character: Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS
The W205 facelift C 63 S Saloon combines a 375 kW V8 with rear-wheel drive. Its MCT gearbox uses a wet start-off clutch. Adaptive damping and an electronic rear differential support its performance character. This entry represents the petrol V8 saloon.
The Porsche 718 Cayman GT4 RS represents the apex of the 718 platform, transplanting a 493hp naturally aspirated flat-six from the GT3 into a mid-engine chassis. The result is a machine with staggering agility and a turn-in response that makes even the standard GT4 feel soft. The chassis balance is dominated by rear-end grip and sharp, responsive steering that provides constant feedback. It is an extreme instrument, demanding a high level of expertise to truly extract its full potential. The power delivery is frenetic, culminating in a high-revving wail that defines the car's racing-inspired character.
Head-to-head, the division is clear: the Mercedes-AMG C 63 S Saloon — 4.0-litre twin-turbo V8 and rear-wheel drive; the Porsche 718 Cayman GT4 RS — High-revving 4.0L flat-six; mid-engine platform provides superior agility compared to rear-engined counterparts. Characteristic of the Mercedes-AMG C 63 S Saloon: Nine-speed MCT gearbox and electronically controlled rear differential. For the Porsche 718 Cayman GT4 RS: Induction noise proximity; intake plenums directly behind occupants intensify the driving experience. In outright terms it is 503 hp against 493 — a 10 hp gap — and the Porsche 718 Cayman GT4 RS reaches 60 mph 0.6s sooner.
Interior & Cabin: Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS
The cabin follows the W205 dashboard layout. It uses a separate central infotainment display and centre-console controls. Trim and seat specifications depend on equipment. Portrait MBUX and W206 hybrid descriptions have been removed.
The interior is a study in weight reduction, featuring CFRP door panels, lightweight door pulls, and carbon bucket seats that lock the driver in place. The presence of the standard roll bar behind the seats signals its intent, creating a sparse, motorsport-focused atmosphere. Sound deadening is intentionally minimal, allowing the mechanical symphony—and the roar of the intake located just behind the driver's head—to flood the cabin. It is not designed for luxury or comfort, but rather as an extension of the driving experience, prioritising tactical feedback and material efficiency above all else.
Head-to-head, the division is clear: the Mercedes-AMG C 63 S Saloon — Four-door W205 cabin with separate central display; the Porsche 718 Cayman GT4 RS — Lightweight door pull designs; carbon fibre trim reinforces the purpose-built racing architecture. Characteristic of the Mercedes-AMG C 63 S Saloon: Facelift instrument and steering-wheel controls; equipment varies by car. For the Porsche 718 Cayman GT4 RS: Fixed-back bucket seats; cabin layout restricts movement to ensure ideal driving posture.
Daily Usability: Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS
The UK specification lists a 435-litre boot. The four-door body supports daily passenger use. This V8 model has no plug-in charging or electric-only mode.
Daily utility is significantly compromised by the track-oriented nature of the GT4 RS. The suspension is exceptionally firm, making it punishing on all but the smoothest road surfaces, and the lack of sound insulation makes it unsuitable for long, tedious commutes. Despite this, the front and rear trunks remain available for storage, and the inclusion of a front-axle lift system helps navigate urban obstacles. While it is technically possible to drive to the track, the RS experience is best reserved for spirited road use or dedicated circuit days rather than routine errands.
Head-to-head, the division is clear: the Mercedes-AMG C 63 S Saloon — Five-seat saloon layout and 435-litre boot; the Porsche 718 Cayman GT4 RS — Balanced mid-engine weight distribution; 125L boot space accommodates smaller luggage bags. Characteristic of the Mercedes-AMG C 63 S Saloon: 11.8-metre turning circle in the UK brochure. For the Porsche 718 Cayman GT4 RS: 110 mm ground clearance aids accessibility; compact 4379 mm length eases urban maneuvering. that means 435 litres of boot space against 125, plus a usable front boot in the Porsche 718 Cayman GT4 RS, and everyday running costs that favour the Mercedes-AMG C 63 S Saloon at the pumps.
Ownership: Mercedes-AMG C 63 S Saloon vs Porsche 718 Cayman GT4 RS
This is a petrol V8 ownership profile. Hybrid battery warranty and electric-range claims do not apply. Existing price history is retained for the separate pricing review.
Owning a 718 Cayman GT4 RS is a high-stakes proposition, with high purchase prices and significant service costs reflecting its status as a low-volume, specialised performance vehicle. Values have appreciated rapidly, as the model occupies a unique space in the modern Porsche lineup. Owners benefit from the comprehensive Porsche Motorsport support network, which is essential for managing RS-specific components that are more expensive and harder to source than standard parts. It is a collector's dream, provided the owner acknowledges the substantial overheads and the demanding nature of maintaining a high-performance track machine.
Head-to-head, the division is clear: the Mercedes-AMG C 63 S Saloon — Mercedes-Benz servicing and AMG component support; the Porsche 718 Cayman GT4 RS — Strong brand reputation; dealer service intervals are predictable for the mid-engine platform. Characteristic of the Mercedes-AMG C 63 S Saloon: Confirm service history, tyres and brake specification on the individual car. For the Porsche 718 Cayman GT4 RS: High resale demand; specialized Porsche engineering creates long-term value for automotive enthusiasts. On the wallet the two diverge at £55,000 versus £115,000 — a £60,000 difference, with annual maintenance of £1,100 against £1,300.