Facinating to see someone reads my tripe!
sammyb; I see you have a personal investment in the Corvette, don't be too insulted by my "noise", I'm just not impressed with this particular phallic device. Besides, I drive a Ford Escort as my daily driver!
However, a Corvette has NEVER won at Sebring or LeMans with or without factory support. Their best finish was third at Sebring in 1973, behind not 1, but 2 - 2.8 liter, naturally aspirated, "privateer" Porsches! They have been unsuccessfully factory entered at this course many times, starting, I think, in 1956 complete with Duntov presiding. The Corvette was the "bright hope" that year at Sebring. The Corvette team reported rack times 4 seconds faster than anyone else during testing. When it came time to race they were much slower and eventually finished 9th.
Corvetts have not been routeinly factory sopnsored at LeMans, because, they are so embarrasing at Sebring, they never leave US soil! Yes, they win their class (sometimes, inclucing Sebring 1956), but the best they have finished overall at LeMans is 10th on a "speed" track, behind Vipers in the same class and with four 3.6 liter Porsches right behind them. Corvetts may have the highest winning record for Factory sponsored teams, but Porshe is the winningist marque: Ever.
Now that I've insulted this False Idol again, let me add that my point is that both Ferarri and Porsche (as well as others) have the philosophy of: We build cars to race; want to buy one? While GM seems to have the philosophy of: We build cars to sell; want to race one? This thought is re-enforced by your mention of the factory going to LeMans only 4 times.
My personal opinion is GM is lost, lost, lost, because of the underlying meaning of this philosophy. They once dominated the industry, but they have forgotten what automobile brands are for. Everyone should not be able to afford a Cadillac (that's what Buicks are for)(Ever seen a Cimmaron?). Show me a Pontiac and a Chevrolet that aren't "brand engineered" like Austin and Morris used to be (Look at what happened to BMC). Oldsmobile expired, just like your grandfather, because it was left to grow old and not innovate.
Corvetts are performance cars; spend the money; race and improve them, make them dominant, not some wishful 7 liter monster, that can't last 24 hours against cars with 1/2 the displacement. Build a compettive Corvette prototype and campaign it to the world championship. Nissan, Toyota, Mazda, Ford (althought not recently) have all done it; what's wrong with GM?
FYI Most laps led @ Sebring:
Porsche - 3997,
Ferarri - 2743,
Audi - 1412,
Nissan - 1111,
...,
Corvette - 112,
Oldsmobile - 13,
Cobra - 1
Cadillac - 1