Tire pressure, and other tips
peakbagger said:
I would like to reinforce, Neil's comments. Yak racks and Thules are removable. Leaving them on all the time affects gas mileage especially at highway speeds. Slowing down from 85 to 65 makes a big difference also.
Also -- check your tire pressures... take them at least up to factory recommended pressure (usually on the driver's door jamb), and seriously consider pumping them up to a higher pressure (though never any higher than the limit on the sidewall -- COLD). Increasing tire pressure decreases rolling resistance, and can improve highway mileage by as much as 5%.
Disadvantages: it will make your ride noticeably harder, and, if you over-inflate, can cause odd tire wear.
I run my Volvo's tires in the high 30PSI range all the way around, have no issues with tire wear, and consistently see highway mileage at the top of the EPA rating for the car, which isn't typical for the older rating system.
There are other, common-sense, no-cost and low-cost things you can do, too:
*Don't run the air conditioner if you don't need it. Most newer cars automatically with electronic A/C turn on the compressor when you hit "Auto". The A/C can cost you 1-3mpg on the highway (though there's the perennial debate of whether driving with the windows open causes more drag...)
* Make sure your air filter is clean and breathing properly. If it's been a while, check to see the tune-up interval for your car -- most newer cars, it's 60k or more miles -- but when spark plugs start to go, mileage plummet.
* Use cruise control and leave a good buffer between you and the vehicle in front of you on the highway, so you're not constantly adjusting your speed. Slowing down and speeding up is a terrible waste of fuel. Drive like you paid dearly for every bit of acceleration -- you did.
* Don't carry excess weight (more weight=more energy to move it) -- so you can probably ditch those two sandbags from the back of the pickup.