I purchased my first car last year, and have a 36 month finance on it that I'm currently paying. How does this work with the Major Purchases section?

[timgmeyers]

I am also trying to figure out where to find the numbers for "Cost Excluding Tax" and "Sales Tax Paid".

[AnnetteB6]

If you are claiming itemized deductions on your return instead of the standard deduction, then adding the sales tax that you paid for the car may be beneficial.  

When you are working through the possible deductions, TurboTax will compare your state and local taxes withheld versus your sales tax deduction based on where you live.  If the sales tax deduction is more beneficial, then you can add sales tax paid on major purchases, such as your car.

You should be able to find the values you are looking for in the paperwork from the purchase of your car.  However, be aware that some states limit the amount of sales tax that can be charged on a vehicle purchase and some states do not charge sales tax at all, so it may not be as beneficial as you expect it to be.

[timgmeyers]

So, if I'm not doing itemized deductions, should I even bother filling this out?

[DMarkM1]

That is correct.  Sales taxes paid are an itemized deduction.  If you are not itemizing, there is no tax benefit.