Heh, a cube (1 meter ^3) of earth is still going to be a trifle difficult to avoid if you're speeding away down that nice, long, straight highway.
And who said it had to be easy to avoid? Say hello to "Mr Tanktrap."
And for flying vehicles, a decent force Toxic Wave/Spray tends to do more bad things than most riggers want to think about. Aftr all, those air-intakes are open, after all...
But if you're in a panzer you've spent millions on, ok, I get the whole "I'm indestructable" vibe.
I tend to think that's it's asking for a major spanking, but that's my view.

"If you build it - they will want to break it. Or steal it. Or bury it..."
Oh - another suggestion by my local anarchistic mage - Glue. I was thinking icesheet and lightning, but Glue is so much more...humiliating?
"Yeah? Cop THIS!"
Out of interest, can any mages out there tell me if sensors (visual) can "see" through a force 5 Gluebath?
"Let's see that <Insert "death from above" attack chopper> fly now!"
...And not many T-birds have autogyro, do they..?
L - Just don't ask what she did with a force 5 power foci, shape earth and a fast-moving convoy of trucks.