Tips for saving fuel on road trips: What's real and what isn't

Gasoline costs are hovering near $4 a gallon this week, and drivers hitting the highway for the holiday weekend are looking for ways to save.

In preparation for Memorial Day, the Consumer Federation of America has released a list of tips that will help you pinch pennies at the pump.

Most of these are the same evergreen recommendations that pop up for every road-trip holiday, and some of them are getting a bit stale. Let's separate the 2011 facts from the circa-1977 facts:

1. Check Your Air Filter

CFA: A clean air filter can improve fuel economy by as much as 10 percent, and nearly one in four cars need an air-filter replacement. Changing a dirty air filter can save the equivalent of 39 cents a gallon or carry you 23 more miles on a typical tank of gas.

AutoWeek: True. But if your air filter is dirty enough to restrict flow to the extent on which CFA bases its claims, chances are your tires are also half-flat, you haven't changed the oil in 40,000 miles and you purchase fuel in $5 increments. So a dirty filter is the least of your concerns.

2. Straighten Out

CFA: Poor alignment not only causes tires to wear out more quickly, it also forces your engine to work harder, which can reduce fuel economy by as much as 10 percent. Fixing improper alignment would be like saving 39 cents per gallon.

AutoWeek: Ever seen those trucks crab-walking down the interstate thanks to a hopelessly bent frame? Those are the ones that would benefit 10 percent.

3. Tune Up

CFA: A properly tuned engine can improve mileage by 4 percent, which is like saving 15 cents a gallon.

AutoWeek: If you've hit your tuneup interval, by all means get it done. But with most cars built over the past five years, those intervals are at 100,000 miles or more. Even then, they involve little more than plug replacement and perhaps a fuel-injector cleaning. Follow your manufacturer's recommended maintenance schedule and you'll be fine.

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CFA: More than one-quarter of vehicles have improperly inflated tires.

4. Pump 'Em Up

CFA: More than one-quarter of vehicles have improperly inflated tires. The average underinflation of 7.5 pounds causes a loss of 2.8 percent in fuel efficiency. Properly inflating problem tires is like knocking 11 cents off a gallon of gasoline.

AutoWeek: We're not sure about their math, but you'll get no argument from us on this one. In fact, we'd be surprised if the actual underinflated-tire number was as low as 25 percent. A tire pressure gauge is one of the most important items in your toolbox.

5. Check Your Cap

CFA: It is estimated that nearly 17 percent of cars on the road have broken or missing gas caps, which reduces fuel economy as well as possibly harming the environment. Fixing or replacing a faulty gas cap is like saving three cents per gallon.

AutoWeek: With the vapor-control systems so closely intertwined with engine-control computers on modern vehicles, something little like the gas cap can cause some wacky effects. Just replace it if it's missing.

6. Lose Weight

CFA: For every 100 extra pounds carried around, your vehicle loses 1 percent to 2 percent in fuel efficiency. For every 100 pounds you unload, you're saving the equivalent of six cents per gallon.

AutoWeek: We'll take the spare tire out, but we won't stop eating the Cool Ranch Doritos.

7. Don't Speed

CFA: For every 5 mph you reduce your highway speed, you can reduce fuel consumption by 7 percent. If you typically drive 70 on the highway and slow down to 65, it's the equivalent of saving 27 cents a gallon.

AutoWeek: Yeah, but . . .

LAT Photographic
Smooth driving is a characteristic shared by successful race drivers.

8. Drive Smoother

CFA: The smoother you accelerate and decelerate, the better your gas mileage, with potential gas savings of 33 percent on the highway and 5 percent around town. Consumers who currently drive erratically can pocket the equivalent of 68 cents a gallon by driving more smoothly.

AutoWeek: This is another recommendation we can get behind. Aside from the fuel savings, the ability to drive smoothly also helps boost consistency and is a trait of pretty much every successful race driver. Smooth doesn't have to equal slow.

9. Foot Off

CFA: Riding with your foot on the brake not only wears out your brakes but can also up gas consumption by as much as 35 percent. If you kick the habit of driving with your foot on the brake, you'll get the equivalent of 1.35 cents per gallon in savings.

AutoWeek: Does anyone actually do this?

10. Don't Idle

CFA: If stopped off the road for more than 30 seconds, turn off the engine. Don't “warm up” your car before driving; it is not necessary. For every two minutes that you don't idle, you'll save the equivalent of nearly one cent per gallon.

AutoWeek: If you're parked at school waiting for the kids? Sure. But if you're in traffic and switching your car on and off every time you're stopped for more than 30 seconds, that starter motor is going to cost you a lot more than the gasoline. Plus, it's dangerous. Buy a hybrid with stop/start functionality if you're that concerned.

Bottom line? Most of these recommendations are no-brainers for the kind of folks who read AutoWeek. If you nail it at every light, your mileage will go down--simple.

What's more sobering is the number of folks who aren't aware of these Cars 101 basics, or who might misinterpret them. Remember that this weekend when the guy in front of you has to restart his car after the light turns green.

By Julie Alvin and Andrew Stoy