In almost all certainty they have volume commitments out months - and have for at least two years.
JIT stopped being a reality a while ago.
If you know you're sitting on 2 months of inventory, and you're getting shipments that are equal to 1 month of capacity every month, and it takes 3-5 weeks by sea, it's a perfectly reasonable thing to do still.
Also, depending on their contracts, they may not pay the vendor until they receive the goods at their location, so the sea freight shipment doesn't have a cost for time value of money.
If you're sitting on a buffer, time value of money doesn't matter - and only gets worse by spending more money to get it sooner if you can only produce say 5k cars/week - doesn't matter if you get parts sooner you can't use.