There are already rumors circulating that the racing conversion Ford will get 30% better fuel mileage than the Corvette, and probably be a bit faster too. Le Mans has become a fuel mileage race as much as anything. Of course, if the Fords or Corvettes should dominate their class, you can bet the rules will be changed to favor the Euro teams. That's been the case in FIA racing for 50 years.
When 10 Shelby Cobra Daytona coupes and 289 roadsters were entered in the last race of the 1964 season at Monza, they had beaten Ferrari into submission and Ford was just 6 points behind in the Manufacturers championship. The Daytona coupes had already practiced at faster lap times than Enzo's cars could attain, even in qualification trim. Ferrari knew that Ford was going to beat him badly. So, he demanded that the FIA reclassify the 250 LM as a GT car or he would pull his cars from competition. The FIA did one better and cancelled the Monza race, handing the GT championship to Enzo. Ford and Shelby were livid. In 1965, the Cobras brutally crushed Ferrari. For 1966, the FIA again restructured the GT rules (those damned Americans will learn the hard way, right?)
Combine the duplicity of the FIA and Enzo's reneging on his deal to sell out to Ford, Ferrari sat in Ford's crosshair for years. After the 7 liter GT-40 MK.II and Mk.IV crushed Ferrari like a bug in '66 and '67, Enzo, cried like a girl and the FIA banned the big block engines for the 1968 season. Meanwhile, Porsche had rising steadily with their 904, 906, 907, 908, 910 and 917.
So what happened? 5 liter GT-40s won Le Mans anyway, and repeated it again in 1969 (Jackie Ickx brilliantly out-driving Hans Herrmann and his Porsche 908). Ferrari spent a great deal of money to build the 512 series cars. However, the GT-40 was largely outmoded and the Porsche 917 had been sorted by 1970. Not only was Ferrari out-classed by Porsche, his 512s were hard pressed to beat old Lola T70 Mk.III coupes running American V-8s. Hans Herrmann got his win in 1970.
What I miss most is the Can-Am series, from 1966 through 1974. Rules? No rules, really. The fastest road racing cars on earth during that time period. Formula 1 speeds paled in comparison, especially on long, high speed courses. McLarens, Lolas, Chaparral, Porsche, Shaddow, March and even Ferrari (never competitive, but game) were the big names. Anybody who was anyone in racing ran Can-Am. How fast were the Can-Am cars? In 1969, the fastest lap turned at Watkins Glen by a Can-Am car was 1:02.2 in 90 degree temperatures. Later in October, in 50 degree temperatures, the fastest F1 lap was 1:04.4. The average speed of Denny Hulme's M8B McLaren was fast enough to have lapped the entire F1 field over the 200 mile race. By 1973, the Porsche 917/30 was producing as much 1,480 hp in qualifying trim. The Chevys could manage about 1,000 hp in race trim.
Watch this video of Can-Am cars running a vintage race at Infinion Raceway. The 917/30s are fast, and driven hard. That Shaddow Mk.II (1971) was awesome quick too.... Detroit iron, shaking the earth.
https://www.youtube.com/watch?v=6C02jDvfBHUThen, take a ride with Jim Pace (winner of Sebring 12 hours and Daytona 24 hours in a Riley & Scott) in an Oscar Kovaleski's M6B at Road America. Many of these guys race to win... Pace sure does. This car was built for the 1968 season.
https://www.youtube.com/watch?v=wI1up3ukikUPace runs a hot lap at Indy, winning the race.
https://www.youtube.com/watch?v=XxVcsQ9GDaQFinally, race with Pace in a gorgeous 1966 Lola T70....
https://www.youtube.com/watch?v=6DN4BUBF_Xo