Just registered to say this is my favourite of the TC18 candidates. I hope it wins, and I'd like to see it made as a kit some day. It's got this LEGO vibe to it.
One thing I would try to improve is the lower edge of the front bumper to be more of an arc, maybe using the toothed arc (24121) as a base for it.
Also location of the steering input seems a bit inconvenient, but I think that moving it to the top, at the back of the canopy, wouldn't change much for the convenience, but could break the effect.
Anyway, good luck in the competition.