Lotterer was third in the dying stages of the race, which was won by Oliver Rowland for Nissan e.dams, but was in danger of running out of energy in the closing stages.
He staved off the advances of Rast while the Audi driver was running in the higher power attack mode, but then Rast muscled his way through in the second sector on the last tour. The two made repeated contact before Rast closed Lotterer out on the exit of Turn 15 to score his maiden FE podium, having returned to FE for Berlin to replace sacked driver Daniel Abt.
Lotterer, who finished fourth by 0.3 seconds, said: “I made my way forward [from seventh on the grid] and found a good rhythm. I found myself in third place and going well, but I had to burn a bit of energy to put myself in this position.
“On the last lap, Rene just drove into me. He put the nose in. Luckily I saw that because if I would have not seen it he would have just sort of spun me around. So maybe [it’s because] he comes from touring cars.
“Not cool, but he was up on energy so that’s what put me vulnerable in the last lap.”
Rast defended the move – that was ruled a racing incident after a stewards’ investigation – saying he no longer wanted to be a “punching ball” in FE.
“I knew I had to try something, and I dived in…