First up, it loos like the road is open 4/26 - 11/30 from 8 AM to 6 PM. Ha! Guess it's still open for the fall color, then.
Oooh, pretty!. (Yeah, I'm feeling squirley and ready for a vacation. It wasn't obvious before?)
The link above also gives the location of a second gate, which appears to always be closed (no through traffic). I think this is around the downhill start, but I would need to grab the manga and check. At any rate, it's on the town boundries, and there is a 10-car parking lot just a little ways ahead of it. (The parking lot is there presumably for hikers to be able to park before heading into the no-driving section.)
Beyond the second gate (in the no-cars section), the road turns to dirt. Good for hiking. Unusual for car racing.
Hm, Momiji Line appears to be free after 7 PM. Otherwise, it's either 400 yen, 650 yen, or 700 yen, depending on which web page I look at.
A map with a useful parking lot marked on it. (Or so I hope.)
Oh, hey, me? The green part on the signs changes, depending on where you are. Isn't that useful?
Oooh, lookie! Another photo site that actually got caught jaded little me's attention. The text gives useful information. And I particularly like their car.
Hmm... Approximate distances. I like approximate distances. This is one to read the text on. The pictures are pictures, but the text gives useful information!
According to this page the road was completed around July, 2001. Interesting.
Mmm, this looks like my kind of scavenger hunt!
End of the day, time to leave. Not so many links here, but a lot of useful info to chew on.
Oh, and the conclusion of how it's pronounced? Logically, it should be "Shiona", since it's a combination of "Shiobara" and "Nasu", since the mountain sits in between the two of them, in the Nasu-Shiobara region. But everyone who has been there calls it "Enna", and I've seen it romanized "Enna" on a couple of maps. So the verdict is: It's pronounced "Enna".