I do not know why TurboTax doesn't ask for state income tax refunds under Wages & Income nor do I know why TurboTax doesn't ask for vehicle registration fees under Deductions & Credits. They seem to be oversights in the guided process. However, I can show you how to get to them.
To enter your 2017 State Income Tax refund click on Federal (left column), click on Wages & Income (top row), click on "Skip to see all income" (bottom interview pane), a list of options should open up, click on Other Common Income, click on Refunds Received for State/Local Tax Returns, click on Start. I will warn you that if you itemized in 2017 then TurboTax will attempt to determine if your refund is taxable by referencing info off your 2017 return. There is a glitch in the presentation when you enter values from your Federal 1040 lines 44, 45, and 46. Line 47 should show what you get when you add lines 44, 45, and 46. But, for me it did not. To force it to show I had to select Continue and then select Back. Only then did line 47 populate with the correct number. I believe it is a presentation issue and not a calculation issue. Apparently the page does not update until it is completed and Continue is selected.
For Vehicle Registration Fees a similar process is required. Click on Federal, click on Deductions & Credits, click on "Skip to see all tax breaks" (bottom interview pane), click on Car Registration Fees. Then follow the instructions.