How much WVO do you guys get at what interval?
 

That's basically the question. I don't envision driving the car more than 100 miles a week, though I could see ditching any thought of driving for economy if I got free fuel :). Still, I doubt I would use more than 5 gallons a week. Is this a manageable rate, or would I just be accumulating more and more unused WVO?

Depends on your source(s), and how often they turn over how much oil. Fryer oil usually comes in plastic containers (cubies) w/ a cap & handle, 35 lb or a bit short of 5 gallons. My source drains the fryer back into these when the used oil is cool enough. This is the most convenient way to get small quantities. People into large quantities will put out & collect barrels or use a vacuum pump to suck the contents of a collection barrel or dumpster into a tank, like a hot water heater.

Find a good source
 

Find a good source than you can figure out what to do with it. I take home about 30 gallons from my work every day that I work. Sometimes my wife bring home some also. I filter 30 gallons 4 or 5 days a week and the ready to go drum never has as much as I need to filter.

5 gallons a week is $20 worth of gas and not even worth the effort of collecting and filtering.

I drive 600 miles in a week easy and my wife drives 750 plus. Give or take some. Going out of your way is not such a hardship when the fuel costs 3 cents per gallon.