If you purchase in PA and then register in NYC, you will undoubtedly pay sales tax on the purchase price of the vehicle at one of the highest tax rates in the US. As others have said, look up LLC and Montana. That will probably be your best bet.
PA does allow you to purchase in PA and then register the vehicle in another sate, without paying the PA sales tax, which is 6% or higher -- depending on local taxes.
Chet18013