French Grand Prix 

The engine, while powerful, continued to be the main problem for Lotus that year. As usual, the car responded well during qualifying, securing a second position for Ayrton Senna at the 1985 French Grand Prix start.
From then on, the driver conducted gas consumption tests to take the gas-guzzling Renault engine to the end of the 53-lap race. He worked relentlessly on Saturday to ensure a good performance on Sunday.
He realized that he would need to preserve the maximum amount of gas possible until the middle of the race and afterward receive, through signs, new calculations from his team to know the appropriate amount of acceleration he could perform until the end of the race.
Ayrton Senna started the race intending to follow team plans, but the engine failed around the 26th lap in the middle of the famous Mistral Straight. This time, the calculations did not work out.