To get a more precise answer, you need to specify what you mean by "most expensive":
* Most expensive ever sold at auction? This changes frequently as rare cars come up for sale.
* Most expensive new car? This typically refers to limited-production hypercars with extremely high price tags.
* Most expensive car in a specific category (e.g., classic cars, electric cars)? This narrows the field considerably.
Once you clarify your question, a more specific and helpful answer can be provided.