We learn a little more about Lucius's family, as well as a bit about the history of the fictional Yoknapatawpha County. But most importantly, we learn about Boon Hogganbeck.
Nobody knows where Boom came from. He sort of just showed up one day, already giant in size at age ten or eleven. (Nobody even knows how old he is, including himself.)
Anyway, we learn that Grandfather has bought an automobile, the second vehicle purchased in the county. You see, the roads at this time were all dirt, and cars, which didn't really serve any purpose other than looking pretty, were merely considered a fad that would eventually blow over.
But Boon is fascinated by the car. In fact, Boon has been fascinated by cars since one passed through the town in the year prior.
Boon falls head over heels for Grandfather's car, considering it to be his "soul's lily maid, the virgin's love of his rough and innocent heart" (2.22). Right.
Boon goes to great lengths to ensure Grandfather that the car is safe in his care. He spends a couple of months driving everyone around.
The following May, Lucius learns that his other grandfather (his mother's father) has passed away in St. Louis.