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, when Boyke Boyer's concept design was chosen and further refined into production form with engineers. During 1991, the final production design for the new 7-series was approved by the board 36 months ahead of 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. In early 1994, development concluded and in May 1994, the 1995 E38 BMW 7-Series was unveiled. Production started on February 17, 1994 on pilot production variants, with series production commencing in the second half of the year