I love reading ads and watching infomercials touting how a magnet on the fuel line, a spinning fan in the intake, a pill in the gas tank or some do-it-yourself bolt-in hydrogen kit is guaranteed to give our vehicles an incredible boost in fuel economy. They must work (at getting some people to bite and buy) or else they couldn’t afford to advertise. It just shows we’re a gullible lot.
The sad truth is that as fuel prices keep climbing toward $4 a gallon, more and more of us search for magic ways to save at the fuel pump without thinking or doing any research. The result is these advertisers and snake oil salesmen get rich while our vehicles still produce the same rotten fuel economy as before.
During my 20-plus years of testing trucks, I’ve tried out a lot of the miracle fuel economy improvers in hopes one held some grain of truth to the claims. None work. That’s also the consensus of the Federal Trade Commission (FTC) and the Environmental Protection Agency (EPA), the latter of which has evaluated or tested more than 100 alleged gas-saving devices and has not found “any product that significantly improves gas mileage.” In fact, the EPA says some “gas-saving” products might damage engines or cause substantial increases in exhaust emissions.
But there are ways to at least maintain your vehicle’s fuel economy, however bad it might be. In fact, you might even find what I’m about to share actually improves your truck’s average mileage numbers over the next few months and shaves a dollar or two off each fill-up. These tips have nothing to do with gizmos or additives. They employ only one thing: common driving sense.
Driving style is the biggest factor in fuel economy. If you anticipate traffic conditions to avoid unnecessary hard braking and acceleration, it’s easy to improve your city fuel economy by 10-15 percent. The reason is simple: Nearly half the energy needed to power your vehicle goes to acceleration. That’s why heavy-footed starts waste a lot of fuel. My tip: Drive like you have a hair-trigger under your right foot.
The same is true for how fast you drive. I’m not a follower. I’m one of those hunters who likes running in the fast lane—or at least I did until the price of fuel at my local gas station hit $4.15 a gallon for diesel. My driving tune has changed. Now I find myself driving a lot like the patrons of those Florida retirement homes.
Even though driving slower isn’t an easy transition, I’ve seen the reward at every fill-up. That’s not surprising. According to my engineering friends at some of the automotive manufacturers who spend most of their days in wind tunnels, more than half a pickup or SUV engine’s power is used to overcome aerodynamic drag. This really comes into play at speeds above 50 mph. Drive 70 mph and up, and you’ll see your truck’s fuel economy falling like a pheasant taken at close range.
This really comes into play when towing a travel trailer or even a load of quads or side-by-sides. It’s common to improve your tow vehicle’s highway fuel economy 2-3 mpg by reducing your cruising speed from 70 mph to 60 mph. At today’s fuel prices of more than $3 per gallon, that equates to saving about 30 cents a gallon on gas for the typical pickup or SUV—or an annual savings of $450-$600 if you drive 15,000 miles a year.
Another free way to improve fuel economy is to keep that tailgate closed. Argue with me as you may, but the facts are indisputable: Dropping the tailgate decreases fuel economy at speeds above 55 mph.
“Our wind tunnel data falls in line with industry conclusions: The tailgate down configuration produces significantly higher drag than the tailgate up (around 2-3 percent),” said Mark Gleason, supervisor/aerodynamics at the Chrysler Proving Grounds. “Although it seems counter intuitive, having the tailgate up acts like a deck spoiler on the trunk lid of a sports car; the tailgate actually raises the pressures on the rearward facing surfaces of the pickup cab and the forward surface of the bed, thereby lowering the drag of the vehicle by 2-3 percent.”
As odd as it sounds, vehicle designers all say the tailgate left in the up, or closed position, actually creates a large bubble of air in the bed that aero engineers call a “separated bubble” or “locked vortex flow.” This invisible bubble of air trapped inside the open bed box actually helps make the pickup more aerodynamic—much like an invisible tonneau cover over the bed box.
Speaking of tonneau covers, the best device you can buy for a pickup to improve fuel economy is a tonneau—hard or soft, it doesn’t matter as far as improving mileage is concerned.
Last year the Specialty Equipment Market Association (SEMA) released a special study where they tested a new Ford F-150, Dodge Ram and Chevy Silverado with and without tonneau covers in a wind tunnel used by a number of the NASCAR teams.
The AeroDyne Wind Tunnel testing results of that sophisticated study showed a tonneau cover reduces drag by an average of about 6 percent. That’s equivalent to improving fuel economy about 1/2-mpg at speeds over 60 mph, regardless of your driving style. The study also tested the tailgate up/down issue; as I mentioned earlier, tailgates in the open position hurt fuel economy.
As a truck-owning group, I believe we tend to overlook tire inflation pressures way too often. The irony is we’re concerned more than ever about improving fuel economy, yet an alarming number of us are driving around in vehicles and towing trailers that have one or more tires dangerously under-inflated.
Recent National Highway Transportation Safety Administration (NHTSA) studies have found that 40 percent of light trucks and 27 percent of cars have at least one tire that is under-inflated by 8 psi or more of the recommended tire pressure indicated on the vehicle’s door placard. It’s scary to think how many trailer tires are also under-inflated.
Under-inflated tires also give fuel economy a big hit. For every 1 psi all four tires are under-inflated, there’s a 1/2-percent drop in fuel economy. Put another way, you can save 10-15 cents a gallon at the gas pump by keeping your tow vehicle’s—and trailer’s—tires at their proper inflation pressure. If your truck or SUV usually takes 25 gallons on a fill-up, saving even a dime-a-gallon adds up to a free fill-up of an ATV about every fourth gas stop.
By the way, over-inflation doesn’t improve fuel economy. But it does increase the chances of hydroplaning and overall poor vehicle ride and handling while accelerating tire wear. So stay to the tire pressure indicated on your truck’s door placard.
If you’re serious about keeping your fuel costs minimized, don’t add bigger, more aggressive tires or a lift kit. Now, I love lifted trucks, but I know how much lift kits and big tires hurt fuel economy.
I’ve seen this first-hand on my own ’07 Tundra 4x4, which has a 6-inch lift and 35-inch tires. Fuel economy wasn’t that swift to begin with (13/17 mpg). But when the lift kit, tires and winch were added, the fuel economy plummeted to 12 mpg city and highway. The greatest factor is the truck’s frontal area is now much higher, which greatly increases wind drag.
Weight also hurts overall fuel economy. The new suspension, bigger tires and wheels, winch, bumper, extra lights and a bed shell added nearly 1,000 pounds to my truck. When carrying around an extra 100 pounds of unnecessary stuff in your truck can reduce fuel economy by as much as 2 percent, think of what 10 times that weight does!
On the bright side, changing over to synthetic engine oils and differential/ transmission lubricants can improve fuel economy. Most of the new trucks and SUVs already have synthetics in their drive trains, but older ones didn’t. Upgrading to a better, more free-flowing engine air filter can also help a little.
I’d avoid investing in cat-back exhausts and cold-air intakes. They do improve power, but the cost invested in such performance parts will never be recouped in fuel savings alone. The same goes for diesel power modules; they’re phenomenal for adding power, but the fuel economy gains usually aren’t there.
What I’ve told you is common sense. Which method or methods you take all depends on how serious you are about improving your vehicle’s fuel economy and reducing the cost of going hunting.
For me it’s just slowing down and driving a little bit more like my grandmother did when she was alive. Somebody behind me might think I’m driving like an old lady, but then I’m the one who has that extra $600 to spend on some nice hunting wear or gear at the end of the year.