Porsche 718 Cayman GT4 / Porsche 991.2 GT3 RS

The Porsche 718 Cayman GT4 makes 414 horsepower from a 4.0L flat-six. The Porsche 991.2 GT3 RS makes 520 horsepower from a 4.0L flat-six—106hp more from the same displacement. Across 86 shared tracks with 10 unique comparison scenarios, the GT3 RS wins by 4.20 seconds overall, and when you filter the comparison data on this page for matched modifications and matched tire treadwear, the GT3 RS wins 79.6% of battles with a 3.27-second average gap.

This is Porsche's hierarchy in action. The GT4 costs $125,000. The GT3 RS costs $198,000—a $73,000 premium (58% more expensive) for 106hp more power, rear-engine physics, race-bred aerodynamics, and the GT3 RS badge that signals you've reached the peak of Porsche's naturally aspirated production lineup before the 911 GT2 RS and GT3 enter forced induction or hybrid territory.

The 106-Horsepower Gap: Same Engine, Different Mission

Both cars use 4.0L naturally aspirated flat-six engines, yet the GT3 RS makes 520hp at 8,250 rpm while the GT4 makes 414hp at 7,600 rpm. That's 106hp more (26% advantage) and a 650 rpm higher redline. The difference comes from the GT3 RS's engine being developed for motorsport homologation—individual throttle bodies optimized for maximum flow, more aggressive camshaft profiles, and internals built to sustain 8,500 rpm operation (9,000 rpm with optional Weissach Package).

Torque tells a similar story: GT4 makes 310 lb-ft at 5,000-6,800 rpm. GT3 RS makes 346 lb-ft at 6,000-8,250 rpm—36 lb-ft more available 1,000 rpm higher in the powerband. Both engines reward high-RPM commitment, but the GT3 RS's extra 650 rpm means it pulls harder for longer through each gear.

Weight amplifies the power difference: GT4 weighs 3,247 lbs (power-to-weight: 7.84 lbs/hp). GT3 RS weighs 3,153 lbs (power-to-weight: 6.06 lbs/hp). The GT3 RS is 94 pounds lighter with 106hp more, creating a 23% power-to-weight advantage that explains the 3.27-second gap in matched conditions.

What the Filtered Data on This Page Reveals

The comparison tables break down performance by modification level and tire treadwear. Note: This comparison has limited scenarios (10 unique) due to GT3 RS rarity, but the data is consistent:

• Matched mod + matched tire (49 laps): GT3 RS wins 79.6%, GT4 wins 20.4%, 3.27s average gap. Relative speeds at 0.11 (GT4) and -0.72 (GT3 RS) show the GT3 RS driver extracting more performance than predicted while the GT4 runs as expected.
• Medium/medium, TW100/100 (24 laps): GT3 RS wins 62.5% with 2.92s gap—the closest matched scenario. On identical slicks with bolt-on mods, the gap shrinks to under 3 seconds. The GT4 wins 37.5% of these battles, proving it can compete when grip is unlimited and driver skill equalizes.
• Medium/medium, TW200/40 (22 laps): GT3 RS wins 81.8% with 5.50s gap. When the GT3 RS runs R-compound slicks (TW40) versus GT4's street tires (TW200), the power and grip advantages compound dramatically.

Use the comparison filters on this page to see the pattern: when tire compound exactly matches and modifications are equal, the GT4 can occasionally challenge the GT3 RS (winning 20-37% of battles). When tire mismatch favors the GT3 RS, gaps widen to 5-7 seconds.

Mid-Engine vs Rear-Engine: Physics and Philosophy

The GT4 is mid-engine: the 4.0L flat-six sits behind the driver but ahead of the rear axle, creating near-perfect weight distribution. The GT3 RS is rear-engine: the 4.0L flat-six hangs behind the rear axle in classic 911 fashion, creating a rearward weight bias that requires different driving technique.

The GT4's mid-engine layout provides intuitive handling—turn-in is telepathic, rotation happens on throttle lift, and the chassis flatters intermediate drivers. The GT3 RS's rear-engine layout creates trailing-throttle oversteer that rewards commitment but punishes hesitation. The pendulum effect of the rear-mounted engine means the GT3 RS rotates faster through corners but requires more driver skill to manage.

Wheelbase reflects this philosophy: GT4's 2,484mm wheelbase is 28mm longer than the GT3 RS's 2,456mm, yet the GT3 RS feels more stable at high speed due to its rear-engine weight distribution. The GT4 is easier to drive fast consistently; the GT3 RS is faster when driven by experts who understand rear-engine physics.

The $73,000 Price Gap: Track Day Weapon vs Motorsport Homologation

GT4: $125,000 for a mid-engine track weapon with 414hp, GT3-derived suspension, and naturally aspirated perfection. This is Porsche's "accessible" track car—$125,000 buys you 95% of GT3 RS performance in a more forgiving chassis.

GT3 RS: $198,000 for a rear-engine motorsport homologation special with 520hp, active aerodynamics (adjustable rear wing, active front splitter), magnesium wheels, and carbon fiber body panels. This is Porsche's statement car—the GT3 RS proves what's possible before regulations or emissions mandate electrification.

That $73,000 buys 106hp more power, 94 lbs less weight, race-proven aerodynamics creating 340+ pounds of downforce at 186 mph, and exclusivity. The GT3 RS appreciates 10-15% annually as a collector's item; the GT4 appreciates 5-8% as an excellent driver's car. Over five years, the GT3 RS's stronger appreciation ($30,000-45,000 gain) offsets part of the higher purchase price.

Aerodynamics and Cooling: GT4 vs GT3 RS

The GT4 uses aggressive aero: front splitter, rear diffuser, fixed rear wing. Downforce is substantial but not adjustable. Cooling is robust for track use but prioritizes usability.

The GT3 RS uses motorsport-grade aero: adjustable front splitter (7 positions), adjustable rear wing (11 positions), larger side air intakes, NACA duct on hood. Downforce is driver-tunable from 340 lbs (low drag) to 456 lbs (maximum downforce) at 186 mph. Cooling is oversized with dedicated radiators for engine oil, transmission oil, and differential oil—this car is built for 20-minute track sessions at full throttle.

The comparison data shows this: at high speeds on fast tracks, the GT3 RS's downforce advantage creates larger gaps. On tight technical tracks where speeds stay below 100 mph, the gap shrinks because aerodynamics matter less.

Ownership Economics: $125,000 vs $198,000

GT4: $125,000 + $3,000 annual maintenance (Porsche pricing) = $140,000 over five years. Appreciates 5-8% annually, exiting at $169,000-195,000 in 2030. Net gain: $29,000-55,000.

GT3 RS: $198,000 + $4,000 annual maintenance (specialized RS parts/labor) = $218,000 over five years. Appreciates 10-15% annually as a collector car, exiting at $319,000-401,000 in 2030. Net gain: $101,000-183,000.

The GT3 RS costs $73,000 more upfront but gains $72,000-128,000 more in appreciation over five years. As an investment, the GT3 RS outperforms the GT4 while also winning 79.6% of matched lap time battles. You're buying both the fastest car and the better investment.

The Verdict

Choose the Porsche 718 Cayman GT4 if you want 95% of GT3 RS performance for 63% of the price, mid-engine handling that flatters intermediate drivers, and a naturally aspirated 4.0L flat-six that delivers 414hp without the GT3 RS's maintenance intensity or collectibility premium. The GT4 costs $73,000 less and wins 20% of matched battles—proving it can compete when grip and driver skill equalize. For track day enthusiasts who want peak Porsche without GT3 RS pricing, the GT4 delivers.

Choose the Porsche 991.2 GT3 RS if you want the absolute fastest naturally aspirated production Porsche below GT2 RS territory, accept $73,000 more cost for 106hp more power and rear-engine motorsport pedigree, and recognize this is a collector car appreciating 10-15% annually ($30,000-45,000 gain over five years). The GT3 RS wins 79.6% of matched battles with a 3.27-second gap, proving the extra $73,000 buys measurable lap time advantage and long-term value.

Use the comparison filters on this page to see that the GT3 RS dominates but doesn't overwhelm: 3.27 seconds when matched, and gaps as small as 2.92 seconds on identical slicks. The GT4 wins 20-37% of battles in best-case scenarios, proving Porsche's hierarchy isn't absolute—it's graduated. The GT3 RS is faster, but the GT4 is fast enough to justify saving $73,000 if collectibility and ultimate lap times aren't priorities.

For the driver who wants the fastest Porsche track car and accepts paying $73,000 more for 106hp and 10-15% annual appreciation, the GT3 RS represents peak naturally aspirated engineering. For the driver who wants 95% of that performance at $125,000, the GT4 delivers mid-engine perfection without the GT3 RS's exclusivity tax.