 After the 1970 season, NASCAR effectively banned the "aero cars", by restricting all five of the limited aero "production" cars to having to compete with engines no larger than 305 cubic inches of displacement (vs. the 426, 427, & 429 inches that the other cars could run), and the competitive history of the Mercury Cyclone Spoiler II (and its fellow aerowarrior rivals) was essentially over.Today, a Mercury Cyclone Spoiler II is a very collectible car.It was a special purpose built vehicle (some have even called it a "showroom race car") with a very strong racing history, that achieved great success during the Aero Wars.