Patriotism plays a big role in deciding what car to buy.
"But patriotism runs deeper than that, particularly for those car shoppers whose love of country plays a big in which vehicle they decide to purchase."
Sub-claim sets up what "that" means for the clause "but patriotism runs deeper than that"
"Independence Day is upon us, and Americans will be celebrating their love of country with family and friends, picnics and cookouts and grand fireworks displays."