I can’t say I often have cause to talk about multiple Nissans. Plus the car is called a Leaf.

Regardless of who is correct or not, the bus advert to me as a British person reads and scans as a spelling mistake or grammar error. Googling to find they’re allegedly talking about Winston Wolfe doesn’t remedy that problem. Plus that would be Wolfes.

It reads as a mistake to me as an American too, and I expect most of us. It’s an artistic choice.