This is not true. Tesla recently released new Model Y [0], and there's a gap in sales because of that transition. The old Model Y was the best selling car of any kind in 2024 globally.
It's either "a new car" or the same model that accounts for nearly all Tesla sales making it "best selling" compared to makers with newer cars and a wider selection. So... which?
[0] https://www.youtube.com/watch?v=vQ6e4-1uuGA