My Subaru gets bad gas mileage. It's 4 wheel drive, which doesn't help. I have sticky tires on it, which doesn't help. I, um, drive it to its fullest potential... which definitely doesn't help. (I have a performance software package that boosts its horsepower, and that, ironically, improves its gas mileage, but that's not the point.)

So you might imagine that with gas prices being what they are, I should ditch the thing and buy a shiny new Prius because the mileage is so much better. (Let's assume that I were lobotomized so that I could somehow live with a car with less than 300hp.)

Well I thought that too, except for the power of spreadsheets. Because the thing is, my Subaru is almost paid off, so within a few months it's going to be costing me zero ... except in gas.

So if we compare two scenarios, one where I keep my current car with its bad gas mileage, and another where I get a shiny new Prius (which I somehow find in the corner of a bathroom stall such that it only costs $299/month to own), I would still need gas to cost over $6 per gallon before that would be worth it.

Don't get me wrong, I want to use less gas. But when the economics are that far away from working out, it's pretty hard to justify right now. Perhaps if I made a kajillion dollars I would feel differently--- or perhaps I just need to wait 6 months and gas prices will be in that neighborhood.