Probably do it with a $10.00 PIC microcontroller, GPS, accelerometer and gyro.
You can get a garden sprayer at WalMart for about $10.00 also and a use pickup for a few thousand..
Or, you could use a large, industrial tank and an onboard compressor to pressurize it (maybe even put the vehicles own AC compressor and magnetic clutch to use here and save about $20.00) if you need more volume..
Or, you could do a million, zillion other things for a few thousand bucks.
This is just complete paranoia, what I am seeing here..
It's amazing. I have never been so ashamed of the US.
I can practically hear people duct taping themselves in their houses as I type.
To be honest, I was wondering why this 'old news' story was being circulated today. There doesn't seem to be any 'new news' in it.
Anyway, it generated an interesting amount of discussion and information. I'm still glad I don't live in a city any more.