So Strabo denies that Iliad 11.699 can allude to the Olympics for the reasons stated, and even modern commentators have followed him. But Strabo’s testimony requires closer scrutiny on the question of whether the Homeric mention of four-horse chariot racing may or may not refer to the Olympics.
four prize-winning horses with their own chariot
going to a prize festival; for they were about to race for
a tripod; but there Augeas the lord of men took them
and sent away their driver who was angry for the sake of his horses.
The fact that the debt for the stolen chariot is owed by Augeas in Elis does not rule out the possibility that the Olympics, or some precursor of the historical games, were the “prize festival” (êeyla) for which the chariot was headed. The Homeric passage does not say that the games to which Neleus’ chariot was headed took place in Augeas’ sovereign territory. It is likely that the festival was somewhere in the region around Elis. In any case, contrary to Strabo, the territory of Augeas might have included Pisatis, the immediate region where the Olympic sanctuary was located. The presence of a tripod prize and not the simple crown of the later Panhellenic games, Strabo’s other objection, also does not exclude an allusion to the Olympics in Homer. Phlegon, writing ca. A.D. 140, testifies that the olive crown was first instituted in the seventh Olympiad (conventionally 752 B.C.).  Burgess includes the passage among those in the Iliad and Odyssey which give “hints of Panhellenic activity at places such as Delphi, Delos, and Olympia, which could be judged to reflect the seventh century,”  I agree that the epics present hints of Panhellenic sites, but Burgess’ conjecture of a seventh century date for the allusions is given without support and is, I will argue, too early for the Olympia reference.
The 8th century uses seem to have been mainly funeral processions and possibly racing, and the vehicle of choice in the eighth century, to judge from vase painting, is the two-horse chariot, or biga. Bronson notes that in Athenian vase painting:
But none of these relatively rare eight-century four-horse chariots is depicted as racing.  The first certain illustrations of chariot racing after the Bronze Age appear only in the first half of the seventh century including a Syracusan aryballos showing four bigae, a Protoattic sherd also probably depicting bigae, and a Berlin aryballos showing quadrigae.  An early seventh century fragment from Athens shows a chariot race with two-horse chariots whose drivers lean forward, and a pyxis lid from the Agora dated about 670-60 B.C. depicts a chariot race.  So the few extant depictions of racing chariots of the eighth and first half of the seventh century are of the two-horse variety.
The François Crater is also remarkable in combining the stories of several traditional oral legends and presumably poetic texts, e.g. the Calydonian boar hunt and the Patroclus Games in one place in a manner in which tales were assimilated into one great body of poetry, the Epic Cycle, during this same period: “Thus a cyclic combination, which was new at the time, has been adapted to fit the invention of the painter.”  Just as remarkable is that the Homeric Iliad, and the Sophilos and Cleitias vases evidence three independent traditions.
Then follows lengthy description of the games in this order: Heracles watching, five chariot racers, a pair each of boxers and wrestlers, a discus thrower, five runners, tripod prizes, the daughters of Pelias, and Iolaus, helper of Heracles, who is the chariot race victor. Noteworthy is the amount of space devoted to the Games for Pelias, literally and figuratively underlining the importance of the mythical contests. Also remarkable is the juxtaposition of those events with the chariot race between Pelops and Oenomaus at the beginning of the same bottom register of the chest. Since the splendid cedar box is decorated in gold and ivory and is kept in the temple of Hera at Olympia, the inclusion of the contest of Pelops is understandable. The race with Oenomaus, also shown on the later pedimental sculpture of the Temple of Zeus, is the most renowned foundational event for the Olympics. By putting Pelops first and then linking him visually to the Games for Pelias on an object in the Olympic sanctuary, we have a reminder of the association and equal authority of these two archetypical contests for later historical games.