Very grey area at the moment. As things stand buyer is only liable for increase it VAT (not import duty, as you are buying from UK).. But doubt that the dealer will cover the additional import tax as the profit margins in a new car are quite slim.
It’s a lot of cash so worth seeking a legal opinion before signing confirm that you can walk away with no fee; If it was me I would hold off ordering until the situation is clear, unless you are 100% sure you want a Cali and are able to cover the additional Import duty in the worst case.
If the import duty is passed onto the buyer, then expect the conversion market will see a boost next year.