Where can I add a vehicle purchase in Turbotax?

Unless this is a business vehicle and you are self-employed, a purchase of a vehicle is not reported. 

You CAN report the Sales Tax if you use State Sales Tax Paid rather than State Income Tax Paid and you Itemize Deductions rather than take the Standard Deduction. 

Were they EV vehicles?   Vehicles you use for your business?  Or personal vehicles?  What are you trying to enter about the cars?