8. The spoked wheel must have become a symbol for fast running and for the warrior Mars who defines spring. The contrast with the following lame Mercury was a necessity.

Earlier, when Auriga was at spring equinox it should have coincided with the 'battle' between winter and summer:

"Ideler thinks that the original figure was made up of the five stars α, β, ε, ζ, and η; the Driver, represented by α, standing on an antique sloping Chariot marked by β; the other stars showing the reins.

But later on the Chariot was abandoned and the reins transferred to their present position, the Goat being added by a misunderstanding, the word Άιξ, analogous to Άιγίς, simply meaning a Storm Wind that, apparently, in all former times the stars α, η, and ζ have portended at their heliacal rising, or by their disappearance in the mists.

Still later to α as the Goat were added the near-by η and ζ as her Kids, the Έριφοι, - an addition that Hyginus said was made by Cleostratos." (Allen)

I think the hide of the Old Goat was a sign that the earlier function of the Charioteer now should be hidden. The fact that Auriga (at all times) was located in the Milky Way gave another opportunity, viz. to tell how once the weak youngster drove the Solar Chariot down into the River.

But the idea of a pair of spoked Sun Wheels was not abandoned:

Here we can count to 32 spokes for each wheel, and if each wheel signifies half a year then each spoke should represent 192 / 32 = 6 days.

64 * 6 = 384 is just enough to cover 13 lunar months (13 * 29½ = 383½).