Hi your second answer is the correct one: "He seems to be able to afford to buy a car."

Used in this phrase "can seem to" is wrong. Usually "can seem to" is used in phrases that talk about deception or misrepresentation. For example: "He can seem to be nice sometimes but really he's a terrible boss." The "can" introduces possibility and implies that he doesn't always seem to be nice. This sentence can be changed slightly with the use of different modal verbs. For example, "He may/might seem to be nice..." which has the sense that the impression happened once and may not be repeated.

can seem to is wrong he seems to or seems to be able to is correct