It's in the middle of nowhere, and it's kind of weird. But Carhenge is also free and open 24 hours, 7 days a week, every day of the year, though they prefer if you'd visit during daylight hours. A gift shop with a bathroom is open Monday-Friday 10am-5pm.
I think it's kind of an after-hours hang-out for local teens.
It's pretty out there in western Nebraska. The nearest town is Alliance, which has mostly fast food. Scottsbluff is about an hour away and has more variety in restaurants and hotels, plus more attractions.
Tell 'em we sent ya!