Few names in the Porsche world and history carry the weight as that of Hans Mezger. His engine design and architecture defined Porsche’s golden age of motorsports, serving as the foundation for countless endurance racers and street-legal legends. It was Mezger’s engines that propelled the Porsche 917 to victory at Le Mans back in 1970 and ‘71, followed by the 935’s dominant stint in the World Sportscar Championship and 936’s wins at Le Mans in the late 1970s. The Mezger unit also helped define Porsche’s Group C stint with the 956 and 962 in the early 1980s and later influenced the mid-engined 993-based GT1 Evo.
By the early 2010s, however, Porsche’s engineering priorities were shifting towards more emissions-compliant powertrains and new platforms. While the GT program for the 911 evolved into the 991 and beyond, it was the 997 GT3 RS 4.0 that became the final chapter to Porsche’s Mezger legacy and is the most powerful naturally-aspirated flat-six engine ever fitted to a road car, setting it apart from every other 911 GT3 RS model. As a result, collectors today view it not just as one of the greatest 911s ever made, but as a milestone for the German brand, where Porsche’s engineering, racing roots, and analog character converged for the last time.
Porsche 997 GT3 RS 4.0: The Final Mezger-Engine 911
Porsche took the wraps off the GT3 RS 4.0 in 2011, and it was a major milestone for Porsche’s GT-boss, Andreas Preuninger, and his team in Weissach. The GT3 RS 4.0 was no parts bin special and featured some pretty substantial upgrades over the standard GT3 models of the time. This track-bred 911 was equipped with the hardware and learnings that Porsche had gained through years of endurance racing and the 911 GT-Series development programs.
Under the hood, a high-revving 4.0-liter naturally-aspirated flat-six engine that put out 500 horsepower and 339 pound-feet of torque. Building upon the 3.8-liter mill found in the standard 997.2 GT3 RS’s 450 horsepower, the 4.0 now came with titanium connecting rods, forged pistons, and the same crankshaft that was used in the 911 GT3 RSR race car. A 6-speed manual gearbox (the only transmission on offer) with taller gearing designed for circuit racing sends power to the rear wheels, with the dash to 60 mph happening in just 3.8 seconds, and top speed was rated at 193 mph. Sitting on 19-inch lightweight forged aluminum center-lock wheels wrapped in sticky high-performance tires, it carries a Nürburgring time of 7:27 minutes, making it faster than the Carrera GT’s time of 7:32, back in the day.
But in typical RS fashion, power and speed are only half the story. A Porsche RS model is incomplete without top-drawer aerodynamic and weight-saving features. The GT3 RS 4.0 featured lightweight carbon-fiber front trunk lid and fenders, bucket seats, lightweight carpets, and lightweight side and rear windows, saving 22 pounds. The result: a curb weight of just 2,998 pounds, with a full tank, with the power-to-weight ratio at 5.99 lbs/hp. For context, this is lighter than a 997 GT2 RS’s 3,020 pounds, despite packing more race-ready hardware. The current 992.1 GT3 RS tips the scales at 3,268 pounds.
More race-derived elements come in the form of lightweight springs and aluminium struts, a lower ride height, wider track, additional ball joints on the lowerlevel of the rear axle, and a substantial fixed rear wing with redesigned endplates, and air deflection vanes on the front bumper (flics), the first-ever on a Production Porsche, which enhances downforce. At speed, these aerodynamic features can generate 426 pounds of downforce at top speed.
997 GT3 RS 4.0 Specs
| Engine Displacement | 4.0 L |
| Engine Configuration | Naturally aspirated flat-6 (Mezger) |
| Horsepower | 500 hp @ 8,250 rpm |
| Torque | 339 lb-ft @ 5,750 rpm |
| Transmission | 6-speed manual |
| Curb Weight | 2,998 lbs (with fluids, DIN) |
| 0–60 mph | 3.8 seconds |
| Top Speed | 193 mph |
Market Value And Investment Trends
Porsche only built 600 units of the 9972. GT3 RS 4.0, with anywhere between 126-141 units coming to the United States, and it carried an MSRP of $185,000 (~$257,000 inflation-adjusted) back at launch. Given its rarity and the halo status of the Mezger engine, the GT3 RS 4.0 has now become one of the most sought-after Porsches of the modern era. Just a few years back, a well-kept example could be found for around $350,000.
Those days are now long gone. As of 2025, low-mileage cars with extensive documentation are changing hands for north of $650,000. Examples with ultra-low miles or a unique spec can command as much as $750,000. According to Classic.com, the average market price for GT3 RS 4.0s sold over the past five years is $554,413. But the doubling in values can also be attributed to a few more factors. Beyond the scarcity and the final swan song in the Mezger lineage, this is also the last analog RS before Porsche adopted electric steering, PDK, and electronic driver aids.
What To Look For Before Buying A 997 GT3 RS 4.0
If you’re in the market for a GT3 RS 4.0, extensive documentation without a doubt would be essential, given the strong collector appeal. Watch out for modifications that deviate from the factory spec. Porsche’s certificate of Authenticity, original sales paperwork, window sticker, and service history are all must-haves. The engine, while durable, was primarily designed for track work, and there is a chance that the car was driven hard. Bore scoring, RMS Seal leaks, and over-rev, possible to attain from the DME report, are all things to inspect before purchasing.
As for the spec, in typical Porsche fashion, the presence of factory options like PCCB (Porsche Ceramic Composite Brakes) or front-axle lift system can significantly impact values. Paint-to-Sample (PTS) cars are particularly rare, with only 39 produced. This PTS GT Silver example with just 341 miles is currently listed on duPont REGISTRY for $2.7m. However, even the standard GT Silver, Carrera White, and Basalt Black examples carry weight, especially against the contrasting red-and-gray graphics, unique to the GT3 RS 4.0.
A Mezger-Engine Buyer’s Shortlist
If you’re willing to look beyond the 997 GT3 RS 4.0, you have several modern Porsche icons with the Mezger touch.
Porsche 996 GT3 RS
- Production Years: 2003–2004
- Production Numbers: ~682 units worldwide
- Average Market Value (Past 5 Years): $206,762
Porsche 997.1 GT3 RS
- Production Years: 2007–2008
- Production Numbers: ~1,106–1,909 units (410: USA Delivery)
- Average Market Value (Past 5 Years): $236,663
Porsche 997.2 GT3 RS
- Production Years: 2010–2012
- Production Numbers: ~1,500–2,000 (541: USA Delivery)
- Average Market Value (Past 5 Years): $246,159
Source: Porsche, Classic.com
FAQ
1. What was the last Porsche to feature the Mezger engine?
A. The 997 GT3 RS 4.0 is the final production Porsche to feature the Mezger flat-six engine.
2. How many 997 GT3 RS 4.0s were made?
A. Only 600 units were produced globally, with anywhere between 126 and 141 units delivered to the United States.
3. Is the GT3 RS 4.0 a good investment?
A. Yes. Due to its rarity, naturally aspirated Mezger engine, and analog purity, values have steadily climbed and doubled since its launch in 2011, and are expected to continue rising.
4. What makes the Mezger engine special?
A. The Mezger flat-six was derived from Porsche’s extensive motorsport program and is known for its durability, dry-sump lubrication, and high-revving nature.
5. Are there other Mezger-powered 911s worth collecting?
A. Yes. The 996 GT3 RS, 997.1 GT3 RS, and 997.2 GT3 RS all feature Mezger engines and are considered highly collectible.