Deductions & credits

For 2106 part II is for Vehicle expenses. Line 16 is for the commuting miles, (a) vehicle 1 and (b) vehicle 2.

You need to revisit the Job related expenses section:

1. Open (continue) your return in TurboTax 
2. Go to Deductions and Credits in the Federal section
3. Scroll down to Job Expenses for W-2 Income
4. When revisiting that section, you will land on the screen Review your job-related expenses info, Click Review
5. Continue until you get to the Vehicle expenses screens.