Feels like it would be a good addition to let the box inherit the velocity of the car, so there'd be a bit of a game to try to drop it at just the right moment. Missing could also dock your pay, perhaps? Currently just cluster-bombing things is perfectly doable :D But then again this is a chill experience - and funnily enough it fit the exploration critera just great, as I ended up just flying around the whole city you made and checking it out! Really, really great use of the assets!