The BMW E38 model was the basis for the 1995 through 2001 BMW 7 Series automobiles. In early 1988, development began on the third generation 7-series codenamed "Entwicklung 99". From 1989 to 1990 styling work was done initially under design director Claus Luthe (through April 1990), when Boyke Boyer's concept design was chosen and further refined into production form with engineers. In February 1991, the final production design for the new 7-series was approved by the board 36 months ahead of 1994 production. On April 27, 1993 German design patents were filed featuring a pre-production prototype as a design representation. Patents were later filed on October 27, 1993 in the United States. Production started on July 23, 1993 on pilot production models and US specification variants on Januar