a parade lap. Instead of halting the proceedings, officials decided to simply extend the number of warm up laps. The race itself ended up having 85 laps of yellow flag conditions, therefore the fuel allotment did not become a factor. 1997: Additional laps were run (unscored) due to a three-car crash on the original pace lap. 2009: When the field came out of turn four for the start, the field was not well aligned in the eleven rows of three. For the first time in modern history, the flagman decided to wave off the start, by displaying the yellow flag. The lap was not scored. The field re-formed, and received the green flag the next time by, with a slightly better formation. Caution periods Through 1978, the pace car was only used at the start of the race, and was not used during caution periods. Since 1979, the pace car has also been used to pack up the field during caution flag periods. The ceremonial driver drove only at the start of the race. During caution periods, when the pace car is utilized to pace the field, a trained official has been the driver. In some cases, the officials utilize two separate pace cars (exactly the same models) one each for the start of the race, and the caution periods. Currently, the pace car driver for the caution periods is the same driver who drives the pace car for the Indy Racing League during all other events. Cars Starting in the mid-1950s, the auto manufacturer who provided the official pace car started selling replica pace cars to the general public. In many cases, the official on-track pace car was modified from its street-legal counterpart. Strobe lights, rolls bars, multi-point harnesses, television camera mounts, two-way communication (for officials), and removing the air conditioning, are among some of the more routine modifications made for the actual pace car. Some official pace cars, however, have undergone extensive performance modifications, including suspension, transmission, or even engine modifications from their production counterpart (the 1990 Chevrolet Beretta is an example of this). Race-duty pace cars may also have the factory fuel tank replaced with a fuel cell, and usually have an on-board fire extinguisher installed. The special edition production replicas available to the public usually come with full paint and "Indy 500" decals, and may be part of a performance package upgrade. In addition, the track