The owner has a sense of humour - note the propeller now fitted to the exhaust.....
I'm guessing that top hinges at the front or back to open up - but I can't see the front fittings are far enough forwards for the screen to clear the bonnet, so maybe it hinges from the back and there are pins under the dashboard to hold the front down.
Andrew
On edit: I should have looked at the Weiner museum:

Wot? No propeller?