@Plato, it’s possibly not a “new” car, ie. made to order at the factory but instead could be a stock car. You should have had an order number or tracking number. There is not necessarily anything wrong with a “stock car” but it can be a disappointment if you where expecting one “made to order” so to speak. I would make sure you check the mileage before giving your PIN and give the car a really good looking over, take your time and dont be rushed. If you’re not happy don’t be afraid to tell the dealer why and if they can’t resolve it then just leave.
How many miles a new car should have is debatable, personally, for me, it should be less than 5 miles, certainly less than 10 miles. All the new cars we have had on motability have had a mileage less than 10 and I think most have had less than 5 miles. The “stock car” that we where misled with had a mileage of 55 miles and it just did not feel or smell like a new car.