The two images @Famine has kindly shared above, aren't at the exact same point. I know they're pretty close but they're not frame for frame comparisons. I can't determine what exactly the car ahead of the Corvette is, but i'll take a guess at it being the Porsche RSR. As for the other two cars that are leading the pack in the first image, it's a little too fuzzy for me to take a guess at what they are, but I believe they're hidden in the second shot by the campervan, as they've already passed the apex by that point. I also think the marshall is out the shot for the same reason, as the cockpit view in the second image is slightly further around the apex.