Fourth generation (A4/Typ 1J, 1997–2005) The Golf 4 was introduced to North America in mid-1999. Available engines for the Golf at its introduction to the American market were a 2.0 L gasoline engine, and a thrifty (48mpg) 1.9 L TDI engine. The latter soon developed a reputation for good low-speed torque and fuel economy, and can operate on alternative biofuels. In 2004 the updated 1.9L TDI PD or "Pumpe-Düse" engine was installed in the Golf and Jetta. The "Pumpe-Düse" or Pump Nozzle was a Robert Bosch extreme high pressure fuel injection system for direct cylinder injection. A 1.8 L turbocharged gas engine was introduced in 2000, along with the 12-valve 2.8 L VR6. At the same time, the 1.6 L 8-valve unit was replaced with the 16-valve unit from the Polo GTI, but detuned to 77 kW (105 PS). The 2.0 L gasoline engine was the base engine in the sportier GTI only as a 1999.5 model. For 2000, Volkswagen opted for the relatively new 1.8 L turbocharged gasoline engine as a base engine for the GTI. The top-of-the-line GLX model was equipped with Volkswagen's torquey 2.8 L VR6, which put out an impressive 174 hp (130 kW). The VR6 engine, with its narrow 15-degree Vee design, was unique to Volkswagen. This engine is shorter and lighter (featuring a single cylinder head) than other V6 engines which benefits the handling characteristics of this front-wheel drive car. For the 2002.5 model year Volkswagen introduced a 24-valve version of its VR6 engine to the North American market under engine code BDE. This engine had the same torque characteristics of the older 12-valve version which had been carried over from the Mk3 Golf under engine codes AAA and AFP. The 24-valve version gained an extra 26 hp (19 kW) over the 12-valve to reach 204BHP. The 1.8T and VR6 models continued until 2005, when the Mk4 platform came to an end in North America. A similarly equipped version of the European 25th Anniversary Edition GTI , called the GTI 337 Edition, was officially introduced at the New York Auto Show and made it to dealers late May 2002 to the US & Canadian markets. For 2003, VWoA produced 4,200 so-branded "20th Anniversary Edition" GTIs and 4000 were shipped to the United States and 200 to Canada. This event, in 2003, marked the 20th anniversary of the GTI's first introduction to the U.S. and Canadian market, some 7 years after the GTI was introduced to the European market.