Yes, you probably also will need to pay county use tax when you register your vehicle.
I've heard about exemptions or deferrals of sales tax, who's eligible for that?
If you are a member of the Armed Forces, the Sales Tax Exemption DTF-803 form provides information and the definitions to defer your sales tax. If this is relevant to your case, you must pay the sales tax when you leave the Armed Forces or you return to New York.