You've just answered your own question, haven't you? If it's a separate car then it can't be the original by definition.

If you completely disassemble a car then reassemble it, is it the same car?

What if you disassemble all of the car except the wheels and reassemble it but with new wheels?

How about if you also exclude the seats too.

At what point does the answer change? That’s the whole point of the ship of theseus.