Ford was really developing the fourth gen Mustang with Japanese partner, Mazda. They envisioned their own import fighter; aero-design, front-wheel drive packaging and with high-efficiency four-cylinder engines! The work started in earnest, Mazda even decided to build a plant in Flat Rock, MI. to produce their MX-6/626 series, along with the 'new' Mustang. Exactly like today's concept tease, Ford did not expect the deluge of outrage when the Mustang/Probe concept designs were revealed. The FWD & 4cyl engines were synonymous to econoboxes, not badass performance cars. Dearborn re-marketed and named the new model as the 1989 Probe.
Probe History
Ford Probe: The History of the Model