Buffy knew it was a possibility, sacrificing herself for Dawn and humanity, and did everything possible to avoid it. And, without the wildcard of Doc, the plan would have succeeded. She was so awed when he showed up at the set. Asked for his autograph and everything. And this is how he treats his fans.
Cars are often potent weapons.
Mostly, I'm glad they left dimension-land. Yeah, it was a bit of a stretch for this show. I'm going to be royally screwed. GG and BTVS will be on at the same exact time. Otherwise they'd have to change the name of the show.