You can get massive points by shooting down aerial enemies to crash into ground targets. Dropping wreckage on tanks can give 96,000 to 192,000 points each. Turrets are worth several million points. The stage 1 tank midboss can give an obscene amount of points by killing everything on it by dropping wreckage on them. Basically, wreckage kills give 64x the point value of normal kills (452,310 x 64 = 28,947,840, as seen in the screenshot).
Destroying targets with your subweapon will multiply the point value by 2x.
Take a look at this screenshot at me getting 91.9 million points in stage 1:

The age of Alluro and JudgeSpear is over.