Lotus driver locked up in last corner, allowing SAV to take the inside line. It was game over from there, the lotus driver didn't want to back off and tried to force SAV to brake early. SAV had inside line, he had the right angle. Lotus should have backed off and stayed in the race and tried to take back 1st, but he opted to try force M3 out of the correct line and in the end... suicided.
Seems the Lotus has either massive heat soak issues, or cannot drive with traffic.... As its only after they started running into traffic that the lotus slowed down.