The 911 GT3 (996.1) introduced the '911 GT3' nameplate in 1999 — a stripped, track-biased 911 built by Porsche's motorsport department and sold in Europe and most world markets, but NOT offered new in North America (US-located cars arrive under the 25-year import rule). Its 3.6-liter 'Mezger' flat-six is a different engine from the Carrera's M96: dry-sump oiling and a crankcase and internals descended from the 962 and 911 GT1 racers, driving the rear wheels through a six-speed manual with a mechanical limited-slip differential and no traction or stability control.

Crucially for a 996 shopper, the Mezger engine does NOT suffer the M96's IMS-bearing or bore-scoring failures — it uses oil-fed plain intermediate-shaft bearings and a race-derived dry sump, and is prized for durability. The GT3 is also lighter and more focused than the standard cars: at about 2,975 lb (1,350 kg) it is roughly 88 lb (40 kg) under a Carrera coupe and about 209 lb (95 kg) under a Carrera 4 coupe, the saving coming from deleted rear seats, a stripped interior with less sound deadening, manual seats and mirrors and no standard stereo. It was the first production car to lap the Nürburgring Nordschleife under 8 minutes (7:56).