Porsche 911 GT3 RS 4.0
Why 2.8: The last Mezger flat-six RS, manual only, 600 built — the reference point every later GT3 RS gets measured against. Values have gone from mid-five-figure used Porsche to six-figure auction piece, and the driving stopped somewhere along that climb.
Layout
Natural habitat
Ride comfort
Sound
The Mezger 4.0 is a detuned race engine — titanium rods, a single-mass flywheel, 8,500 rpm and nothing damping the flat-six behind the seats. It gives up a little range to the 9,000 rpm 992 GT3 and wins it back in mechanical hardness.
6-cylinder · naturally aspirated · 8,500 rpm redline · rated 9.1 / 10 for engine sound
Market value
Median asking price, good condition · €166k (2011) → €478k (2026), trending up · illustrative data
Child seats · ISOFIX
There aren't any — strict two-seater.
On the 997.2 generation, ISOFIX and airbag deactivation were separate order-sheet options that didn't have to be specified together. The RS 4.0's standard fixed bucket seats make it moot on most real cars anyway — Porsche bars child restraints on bucket seats regardless.
Technically orderable, practically almost never usable: nearly every RS 4.0 left the factory with fixed buckets.
PistonHeads "911 (997.2) Child Seat" owner-research thread (owner-community sourced, not manufacturer documentation)
The long version
Porsche built this as a proper send-off for the Mezger engine architecture, 500 horsepower and no PDK option in a car meant to be tracked, and for a few years after launch that is exactly what happened. Auction results over the past decade have rewritten the ownership pattern entirely, pulling surviving cars out of driveways and into climate-controlled collections as the car's status among enthusiasts hardened into consensus. Some owners still track theirs — the community around this specific model skews unusually committed — but a car now worth several multiples of its window sticker mostly gets trailered rather than driven to do it.