I would say, anything whose spacetime geodesic (orbital/freefall path) intersects the spheroid defined by the surface of the Earth. Though by this definition, a comet on a 100-year collision course is already "on Earth", so I'm not sure if that's reasonable.
1.6 tonnes with a combustion engine or hybrid vehicles, and more than 2 tonnes for electric vehicles
There might be silly examples to find, but yours isn't one of them.
I would look for cases where moving from petrol to hybrid pushes you over the limit. I think they should be measuring size and fuel efficiency, rather than weight.
I move away from the atmosphere to breathe in