Development officially commenced later that year, codenamed VX54. The program would replace two existing Nissan product lines developed in Japan (the Van and the Axxess) and Ford would market its version as a Mercury (the VX54 program coincided with the simultaneous development of the WIN88 program, later the Ford Windstar). The final designs were chosen by Nissan in 1989, with both companies commencing testing of prototypes in 1990; real-world testing was done through 1991, as development concluded at the end of that year.