The FW04 was a development of existing Williams FW by engineer and former McLaren designer Ray Stokoe. His contribution was a lighter slimmer and more angular monococque. As a result, the new car was considerably narrower and more streamlined than its predecessor and had its radiators and fuel tanks repositioned for better aerodynamic performance and handling over the earlier car. Belgian oil company Fina was signed as major sponsors with additional funds from a Swiss finance company, Ambrosium. The new Williams appeared partway into the 1975 season. The car was driven by Jacques Laffite, while second team driver Arturo Merzario did not liked it preferring to drive the old FW. In the 1975 German Grand Prix other teams suffered problems and Laffite drove FW04 through to second place. By the time of the season-ending US Grand Prix, a second FW04 had been built, and Lella Lombardi was invited for one-off drive. Both cars failed to start at Watkins Glen. Laffite had qualified 21st but was unfit to race, while Lombardi qualified 24th, but suffered ignition problems and was unable to start.
| Season | Series | Event |
| 1975 | F1WC | USA GP |
| Driver | No. | Entrant |
| Lella Lombardi | 20 | Frank Williams Racing Cars |
| Scale | Manufacturer | Collection |
| 1:43 | Spark | |
| Cat. No. | Quality | Rarity |
| S5930 | 
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