Portland car owners could pay an additional registration fee for their rides -- this one based on how much they drive. We already have a tax that's based upon how much you drive. It's known as the gas tax. You pay it every time you fuel up. But, you see, Portland's politicians (and Oregon's puppet "governor") want to move away from the traditional money source: the gas tax.
Translation: they want to keep charging you a gas tax. They also want other ways to take more money from you. Oh, it's all for a good cause. It always is.