From a racing standpoint it’s kind of like a longer, duller Formula One where faster cars pile up huge time advantages. In endurance this tends to be evened out by mechanical failures and accidents.
There are 4 main classes of cars on the same track at once, Prototype 1 and 2 and Touring 1 and 2. Cars are required to be able to accept a passenger seat, but not to actually carry one.
This year most of the interest is in GP1 where there are 3 distinct types participating. The first is the returning champions, the Audi Quattro Diesels. Conventionally turbo charged. The second is the Toyota Diesel/Electric hybrid. This car is appearing one year early on an accelerated development schedule to mark Toyota’s recovery from the 2011 Tsunami. The third is an Audi Quattro Diesel/Electric hybrid.
Between the 2 hybrids the Toyota is clearly the superior design (though The New York Times disagrees). It uses its electric motors to drive the rear tires through the regular transmission. The Audi on the other hand is a front wheel drive with separate drive shafts that increase mechanical complexity and drag.
Racing in its own class is the Nissan DeltaWing which looks much faster than it drives, qualifying at the tail end of the GP2 pack. Touring 1 (Pro) will be a 3 way contest between Ferrari, Aston Martin, and Corvette. Touring 2 (Am) is dominated by Porsche 911s.
Coverage on Speed will be continuous until the conclusion except for a 90 minute break at 1 pm for Turn Left and 30 minutes at 7 pm for Speed Center.