I don't know... When I did commute a lot, it was like 200-400/week. (Regular commute of about 25 miles + night trips into Portland which added another 45; those were frequent to infrequent)
Even when I used to go out 6-7 times a week in Seattle and drive everywhere, it was only adding up to 200 miles/week because I wasn't far from anything. Of course, my gas mileage was horrendous because I drove like a maniac. So, I still had to fill up every week.
Now? Eh, I barely drive the damn thing on a regular basis. Maybe 5-10 miles a week. But, I still make trips to Portland every few weeks and so that adds 400+ miles (I live in Seattle now). Also, I travel with my car and that adds thousands of miles. (Went to SF and LA in September. That added 3,000+ miles in 12 days.)
I'm looking at over 6,000 miles in what will be a 3-4 week 'vacation'. (Going down to Texas) So, that will also up the mileage quite a bit.
It's complicated...