The appeal Nascar has over F1 and most other forms of racing....
Oval Tracks.
Yes it's all left turns. But you can see most of the track from one vantage point. In road racing, you find your spot and you can see 1 or 2 turns, then wait until the field comes back around to you.
That screws with television coverage too. You get into a flow watching oval track. Road racing coverage jerks you around, cutting from one shot to the next. Hard to get your bearings.
And these all fall under Branding; how a fan connects to the driver/car/team.
Big Cars
It's much easier to quickly recognize the players.
Unique Paint Schemes
Instead of team colors, each driver has his sponsors paint scheme. I don't have to squint to see if the nose cone, or the helmet, or the camera pod is a different color to see which driver I'm watching. Imagine if they did that in NASCAR, if the 24, 48, and 88 all had the same paint scheme. Crazy.
Unique Numbers
Your number is your identity. It's not like you win the No 1 plate and run that number next season. I don't go out of my way to watch Nascar, but I've absorbed enough to know who is who just by the numbers. I bet you all know who drove the 3 car.
And finally....Passing
Passing can happen anywhere in Nascar. Open-wheel racing on road courses usually means just a few places where passing is possible. The rest is a parade.