Honda had made the Constructors' Championship-winning engines of 1986 and 1987, and for 1988 they switched partners from Williams to McLaren, who had struggled with their dated TAG-Porsche engines. With Murray deciding that the base design of the MP4/4 would be inspired by his 1986 low-line Brabham BT55, Nichols, designing around the parameters Murray had set for the car then took elements of the MP4/3 from 1987 using the same design principles, but with more time, different components (smaller fuel tank, smaller engine, for example), and different rules the car was a significant development.