One idea would be to make something up, (i.e. not a real vehicle or object) a concept phone or ship or something. That way you could include only as much detail as you have time for and they won't be comparing it to the real thing. On the other hand, sometimes creating a convincing concept is hard and time consuming.

If your interview is on monday, I would highly recommend getting some sleep over the weekend. I'm sure the interview would go worse if you have a great portfolio but aren't able to function or communicate :p

Anyway, congrats on your progress and good luck with the rest of it!