At least three people had seen the car smashed against the tree on the outskirts of town. They had plenty of time until sunrise, and as long as Spike hadn't done anything incredibly stupid, they should find him with night to spare.
Buffy tried very hard to not think about the worst possible scenario here.
"Giles, it has to be around here someplace. I mean, it's a car and a tree, and we're running out of trees and I haven't seen a car in forever..."