I only fill up my car when it's on E. I know conventional wisdom says you shouldn't do this, although recently I've learned that conventional wisdom is usually useless, but I do it anyway. Because of this I always fill up around 13 gallons (my manual says it has a 14 gallon tank, but I've never seen it go past 13) so I have a good starting benchmark to work with and I can gleam all sorts of interesting data about my car and driving habits.
According to www.fueleconomy.gov my 2002 Subaru Imprezza 2.5RS should get 22 MPG. Now my average mileage per tank is 260 miles which comes out to about 20MPG (I'm using 13 gallons). I'm not that concerned about the below average MPG because I'm good at keeping the car maintained and I know mechanically it's fine. Rather I believe there are two factors that contribute to this. One is where we live, University City, an area that is notorious for horribly timed traffic signals and a high population density, both causing long periods of the car running but not actually going anywhere. The second are my driving habits, which are related to the unfavorable traffic conditions (I jump off the line at one light in order to try and make the next one before it goes into it's five minute cycle).
With such a low MPG, an unfavourable environment, and my impatient self to blame how do I almost go a month without getting gas? Three things:
- Taking the bus to work
- Walking to the bus stop
- Carpool as much as I can
The second factor is I usually walk the fifteen minutes to the bus stop, although sometimes I drive if I'm running late. This adds the addition of health benefits as well as time to slow things down and not get so caught up in things.
I also tend to carpool as much as I can, which usually ends up with someone else driving since my car doesn't have a stereo in it (high crime rate is also consistent with where we live).
When you combine all these factors not only am I only filling up once a month, but I also gain more than if I drove, economically it just makes sense. Now I know that everyone's situation is different and I am lucky enough to work for a commuter friendly employer who provides free bus passes that are convenient to where I live. UCSD also provides free hours with a hybrid Flexcar a month so I can go somewhere during work hours if I need to.
If at all possible I would recommend looking into supporting your local public transportation to not just save money but also increase other aspects of your life.