Not having the 1000G needed to buy one of the cars in the "Endurance Champions" series, I do my farming with the Ferrari F40 (PR 58) in event #21.3 (4 laps) of the "Classic Ferrari Showdown". Fifteen minutes of racing: 30,000 fame points (w/Fame Agent).
Wanted to know if there was another car in my collection that could improve on the lap times I get with the F40 (average: 3:40). A quick search of the forum database uncovered the Porsche 918 Spyder (PR 71) available in the "Spider Showdown" series. Event #20.2 is the only other 4 lap LeMans race. Was able to do a 3:36 lap, total race time of 14:31. In many, many runs with the F40, my fastest time for the 4 laps was a 14:58. My average is 15:10.
So if you're looking for a fast ride around Le Mans and don't own one of those exotic 1000G cars, give the Spyder a try.