Over the last two tanks, I averaged about 33 MPG. The image above shows 39.2 MPG, but that was probably due to a faulty filler that shut off early. That's in a '99 Subaru Outback, a car that is rated at 18 city, 25 highway by the newly adjusted ratings. I used just a couple of techniques in different situations in order to optimize my mileage to this point. I went the speed limit, and I tried to turn the engine off whenever I could without compromising safety. I drove with the air conditioner off, and I rolled the windows up on the highway, using the vent fan but not the compressor to cool myself on hot days. I also inflated my tires to a safe but hard 41 psi, several pounds above Subaru's specification, but still well within the reasonable range for the tires (max cold pressure 44 psi). They actually seem a bit quieter at this pressure, so having them overinflated actually improves my comfort when driving.
The biggest thing I've done to improve my mileage beyond what I normally do is turning off the engine. I've always kept my tire pressures near the top of the range and been mindful of when I was using air conditioning. As previously stated, I've tried to turn the engine off whenever I can safely do so. That means practically all red lights, including the time spent coasting up to them, as well as anytime I'm on a downhill slope steep enough to maintain a comfortable speed. Since my car is wired to turn the headlights off when the ignition is turned to 'accessory', I avoid turning it off at any time that headlights are necessary (night, rain, fog). Even so, I try to gently engine brake whenever I'm approaching a stop.
Slowing down has played an important role in improving my recent mileage as well. There's no need to speed. I always give myself plenty of time when I drive, so there's no hurry. On highways, I go exactly the speed limit or a little under. It is supposed to be an upper limit, after all. I rarely use route 288, the local 65-zone, so it's easy to keep my speed under 60 at all times. Practically all cars with four-cylinder engines like mine are most efficient at 40-55 MPH. This is due to a number of factors, especially wind resistance and engine speed. As a rule of thumb, if you're turning 2500 RPM in top gear, you're probably getting about the best gas mileage you can get.
Literature on hypermiling websites talks frequently about the 'pulse-and-glide' technique. This has proven the most effective way to drive for gas mileage, but frankly, I don't have the balls to do it with any traffic around. I'm not trying to piss off other motorists, just trying to save some money and some fossil fuel. We'll see how this works out over the next several months as I test different brands and types of gas, as well as hopefully get a ScanGauge in order to more accurately track my mileage. For now, though, I'm just excited about my little improvement in mileage.
