a Mercedes-Benz and the other a Mitsubishi. In May 1992, these plans were abandoned citing "technical problems" and Mercedes-Benz continued on with in-house development from January 1993. In March 1993, a search for a location to build a U.S. manufacturing plant began. By September 1993, a location in the state of Alabama was chosen and construction started in 1994. While plans were being made overseas, in Germany development continued. Design work took place from late 1992 to 1994. A design from Mercedes' Sindelfingen studio was chosen in 1993 and approved by the executive board in February 1994. The design patents were filed in Germany on 13 July 1994, and in the U.S. on 13 January 1995. Prototype testing started with test mules and crash tests using mock-ups in May 1994. First functional prototype's crash test took place in February 1995, with full testing run from March 1995 to December 1996 in various climates and regions of the world. Pilot production began in May 1996. In July 1996, construction on the Mercedes-Benz U.S. International plant in Vance, Alabama concluded, with the very first production M-Class rolling off the assembly line the week of 9 February 1997. Initial release Mercedes-Benz launched the first generation W163 series M-Class on 19 February 1997, in the United States for the 1998 model year, with sales beginning that September. It is a mid-sized body-on-frame SUV with seating for five, or seven with an optional third-row, seven-seat version. Access to the third-row was deemed problematic and the seats were not suitable for large adults. As the result, the seven seater ML-Class was discontinued after the 2005 model year and replaced by the larger GL-Class. The Mercedes-Benz M-Class (W163) was available with permanent 4Matic four-wheel drive, which routed torque to all four wheels through all open front, center, and rear differentials. The system used a two-speed dual range BorgWarner 4409 transfer case with reduction gearing, and Mercedes' new Four-wheel Electronic Traction System (4-ETS). 4-ETS simulated three differential locks on all three open differentials, via aggressively braking one or more spinning wheels. The M-Class was the first luxury SUV to feature electronic stability control, a system designed to detect loss of control and instantaneously intervene with selective braking to bring the vehicle back on its intended course. Furthermore, the M-Class boasted front- and side-impact airbags with advanced occupant detection for the front passenger seat, which helped earn the W163