 Complete the following phrase:  During the 1988 season, Williams worked with their new engine supplier Renault to develop the RS1 3.5 V10 engine. Williams designed a test mule for the engine named FW12B, very much like the Judd-powered car Williams used for the 1988 season except the mule was designed to accommodate the extra length of a V10 engine and not a V8 like the race cars used. For the season the Renault V10 engine was used. This was the first Renault powered Williams F1 car and also saw Renaults re-entry into Formula One after stopping the supply of their turbocharged engines following the season. The Renault engine was designed under the direction of longtime Renault Sport engineer Bernard Dudot; the design and development of Renaults V10 started at least a year before Honda began developing their V10 engine largely due to Renaults short-lived withdrawal from F1 as an engine supplier at the end of the 1986 season. The updated and revised FW12C showed its potential in the season opening 