[rsa4046]

The first two seem consistent as tentative responses to a statement that might contain hyperbole, joke, play on words, double entendre, etc., by maintaining some distance with the statement of supercar-as-fact. In contrast, the third seems to accept the fact outright, and lets the accuracy of the responder assume the uncertainty.

[Talanes]

The third reply strips so much away that the tone changes from tentative to apathetic. The third speaker is just doing the bare minimum to keep conversation moving.

[sharken]

My thought as well, the third gives the impression that the person answering doesn't care much for the question.

[reph2097]

That's exactly what a German speaker would do.