[bsims]

This is a fair point, but more often than not people living paycheck to paycheck aren't as familiar with dollar cost averaging and are probably just buying in $20 amounts because that's how much cash they have at that time.

The OP also said it was based on 5+ years worth of data which probably means it is less about gas price fluctuations and more about buying habits.

[uvince]

I apologize for being dense, but what data exactly is the OP crunching here?

[jerf]

Internal private data. We don't know exactly what it is and he can't say.

Really, in the end, this is little more than a moderately well-sourced anecdote.

[uvince]

Thanks jerf, I have no idea why this made the front page. Clearly I have a lot to learn.

[Vivtek]

It has a pretty graph at the top and the guy presumably really did crunch real data, so it gets upvoted. Also it's Brazilian, so it gives you a little taste of 21st-century BRIC economics. Hits a lot of buzzers.