I'm basing it on Musks statements that to get the cars as cheap as possible they need to be manufactured in the appropriate continent. Thats the point of the German gigafactory.

But indeed who knows what the eventual UK Model 3 price will be. Better than it currently is for sure.

Depending on where tariffs land after Brexit, it's possible there's little difference.

GF Berlin will probably be more efficient than Fremont. But so will Texas and whatever comes after.

Don't forget transportation costs too. Not cheap shipping containers full of cars halfway across the world.

Fremont -> Rotterdam is quite a sail!

That's true, although as an individual that costs maybe ~$1k, and I imagine they get much better prices sending them a ship full at a time. I'd love to know exactly how much.

Plus intermediate parts (eg batteries) have to be shipped from China or the US until the factory itself is self sufficient, which may take a few years, and this eats in to the shipping savings. The Gigafactory Berlin plans currently approved do not yet include battery manufacturing.

As far as costs go, shipping is a distant third factor in the US/EU price difference (maybe 2%), compared to the import tariff (10%) and VAT (often >20%).