A Nevada resident can buy a car in sales-tax-free Oregon, and then register it in state, without paying any sales tax.
Uh, no, you can’t.
I couldn’t even buy farm equipment out of state, which has no registration or licensing, without paying sales/use tax in Nevada. You’ll get away with it... for at most a year. Then the assessor comes out to your operation, looks at the list of equipment you’ve declared and what he sees on your outfit, and you get to explain the difference. The best you can get away with is claiming you’re renting the equipment and you don’t own it.
When you go to register a car you bought out of state in Nevada, you’ll get nicked for the tax unless things have changed since I left 2007... which I rather doubt.