Despite spending a fair chunk of time in the south lately, I haven't managed to develop an interest for NASCAR. I could name a few drivers, but otherwise the field seems pretty homogenous. I like the diversity of stories in drag racing - in Top Fuel there's rich and poor, guys and girls, single car teams and multi car giants, owner/drivers, tuner/drivers. Maybe this exists in NASCAR, but I don't know? But I feel like in Top Fuel a lot of people can find a background story that they can relate to. My fiance has little interest in anything automotive, but supports the drivers who were friendly to her in the pits (another fantastic aspect of our own sport that helps people relate to the drivers).
If I went to a NASCAR race, as far as I know I can't interact with the drivers and I really don't know their stories. Makes it hard to develop an interest in the sport.
Building on Samuel's point above, if I do happen to come across posts about NASCAR on Facebook, the comments from fans do my head in. It's not a community of people who seem like they're fun to be around, and if you don't have fun spectating at a race or being a part of that fan community, what's the point of being a fan?