Archive for July, 2007

The Tonneau Cover Fuel Economy MYTH

If you’ve considered buying a tonneau cover for your truck then you’ve probably heard someone tell you that it will improve your gas mileage. They say that because tonneau covers streamline your truck’s bed, they reduce drag improve fuel economy. Too bad it’s a GROSS EXAGGERATION.

Studies have shown that tonneau covers reduce aerodynamic drag. SEMA (the society for aftermarket equipment manufacturers) conducted a study in January 07′ that found tonneau covers reduce aerodynamic drag 4.2-7.8%, depending upon speed. This is the most recent study touted by SEMA, replacing one conducted on a 97′ Dodge Ram nearly 10 years earlier. Interestingly enough, SEMA steers clear of telling us how much fuel savings a “4.2-7.8%” reduction in drag would be. Instead, they say quote: “other tests would need to be conducted in order for fuel economy to be calculated, but it is safe to say that a reduction in drag would improve fuel efficiency for these pickups.”

OUR BS METER WENT OFF when we read that last line. Is SEMA actually saying that they spent the money to test aerodynamic drag on four different trucks, but that they didn’t spend just a little bit more to find out about actual real-world fuel economy savings? Something doesn’t smell right…

Here’s our interpretation of the study:

1) The largest reduction in aerodynamic drag (7.8%) was observed at 85mph. If we’re generous, we could assume that 75% of the engine’s power is being used to overcome the force of drag at this speed (the other 25% goes to tire friction, heat loss, etc.). If drag is reduced by 8%, that would result in a 6% reduction in engine workload. If the truck averages 18 mpg at this speed, then reducing engine workload 6% would improve fuel economy 1.08 mpg. SO, at 85 mph, expect to see about a 1 mpg improvement with a tonneau cover.

2) At a more realistic highway speed of 65 mph, drag is reduced about 5.5%. Using the same math as above but assuming that only half of the engine’s power is being used to overcome drag at this lower speed, fuel economy is improved by 0.5 mpg.

3) At 55mph or below, the fuel economy benefit basically disappears. Aerodynamic drag isn’t significant until you reach speeds of about 55-60 mph. Technically there would be a fuel savings, but it would be small. Less than a tenth of a mpg.

4) Finally, there were 6 different tonneau covers tested. SEMA didn’t disclose which was which, but we’re fairly certain that a fitted, over the rail solid fiberglass tonneau cover gives the best fuel economy results. The cloth/vinyl covers buffet in the wind, and anything that doesn’t go over the rail creates it’s own vortex. Painted to match, these covers cost $700 to $1100 installed.

Now before anyone goes off on us for making assumptions, etc., we did speak with a couple of engineers when writing this article. They emphasized these are rough numbers, and that they could be off by as much as 25%. That means that the best case fuel economy improvement is 1.35 mpg at 85 mph, and 0.63 mpg at 65 mph.

Assuming gas is $3.50 per gallon, here’s how the best case math works out:

Driving your tonneau cover equipped truck at 65mph for 20 minutes per day would save you 0.04 gallons of gas, or about $0.14 per day. Under these circumstances, we figure it will take about 30 years of workday commuting to save enough to earn back the cost of a $1000 tonneau cover.

Drive your tonneau cover equipped truck at 85mph for 60 minutes a day and you’ll save 0.33 gallons of gas, or about $1.16 per day. We figure that’s only 3 years and 7 months of workday commuting to earn back a $1000 tonneau cover. Of course, during that same period, you’ll spend over $13k on fuel. We feel sorry for anyone that has to drive their truck 85mph for 60 minutes a day — the fuel costs for just three years would be enough to buy a nice toy (ATV, boat, motorcycle, etc.).

Bottomline: Tonneau covers DO save gas, but not very much. While the aerodynamic drag numbers sound impressive (4-8% reduction), they don’t actually result in enough gas savings to justify the expense for a normal user. If you buy a tonneau, do it because it keeps your bed dry and secure.

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Toyota Tundra Auto Dimming Mirror

Have you seen this line item on a Toyota Tundra sticker?

• Auto-dimming mirror — MSRP $280

That’s a lot of money for an accessory you can install yourself. Thanks to “Billy Bob” of Lancaster, NY, (a TundraSolutions forum member) we’ve got the low down on the best place to buy the mirror, and some tips for installation.

Aftermarket = Savings

First — where to buy. Your local dealer will charge anywhere from $400 to $600 for these parts, but you can get the exact same Toyota parts from dnd-enterprises on eBay. One tip: Make sure to ask for the long wire cover.

Here’s the link: 2007 OEM Tundra Auto Dim Mirror w/ Homelink and Compass

Price: $229 + Shipping. You can also look at the USA-made Gentex universal mirrors. Skip the compass feature, and you can get the Gentex K2 for about $100. If you want the compass, the Gentex K5 runs about $165. Neither Gentex mirror comes with HomeLink.

Installation

Depending upon your truck, install could be either easy, or very easy. Here’s how:

• Remove the overhead console. Should be four (4) torx-head screws.
• There should be two plugs tucked away behind the console.
• Check to see if the power plug provided with your mirror will fit into one of these plugs. If your truck has the right plug, you can skip the next 3 steps.
• If not, you’ll need to figure out which wires to tap into. Don’t worry, the tap connectors are provided. First, locate the plug with three input wires (it should be clipped into a holder).
• Using a test light or multi-tester, find the ground wire, the constant power wire, and the ignition switch power wire.
• Using the provided in-line snap connectors, attach the provided harness to the factory wiring.
• Remove your current rear view mirror and attach the new one. Run the wires into the liner and attach them to the kit harness.
• Test, then make sure to cover the wires between the base of the mirror and the headliner with the wire cover.

Next, to calibrate the compass, drive around the block once or twice. The compass should self-orient.

That’s it! You’re money ahead ($50 – $130) and you have the satisfaction of knowing you improved your truck. Don’t worry about “messing something up” either — this is a common dealer installed accessory. No problems with warranty, etc. provided you buy the OEM kit.

Thanks again Bob for posting this info on TundraSolutions, and allowing us to paraphrase.

Honda Tuning Magazine’s Readers Rides

We were honored when Honda Tuning Magazine asked us to review their “Reader’s Rides” page. While we aren’t really into the “rice” scene as much as we used to be, one of our site owners, Jason, decided it would be fun to take a trip down memory lane…

To start with, here’s a pic of Jason’s old Acura:

Cool right? Lightning bolts and chrome NEVER go out of style!!

But seriously, that was a fun car for Jason. It was a 94 Acura Integra GS-R, with the VTEC B18C 4cyl. Sure, it was only 1.8L, but it had almost 180 hp. Says Jason “that car was sneaky fast — from idle, it would race to 8300 RPM in first gear in about 5 seconds. The hardest part of racing that car was shifting from 1st to 2nd as fast as you could, which you almost always had to do to win a street race because first topped out at about 45 I think. Anyways, it was fun until somebody screwed up the driver’s door trying to break into it.”

So, needless to say, Jason helped us with this review.

To start with, we don’t like the pop-up that loads when you hit the Reader’s Rides page. We’re not sure what the pop-up says (it was blocked), but we think pop-ups are SO 1997. Anyways, the site loads fast, looks good, and has quite a few pics on it. While there aren’t a lot of vehicles on it right now, it seems to be growing quickly. Our favorite car was Jale’s 2000 Honda S2000 nicknamed “Chuck Norris“. Sharp car, seems fairly stock, but the comments had us laughing out loud. Here’s a taste:

• “Chuck” is my daily driver. When I hit bumps on the road, it feels like a roundhouse kick to the back of my head.
• Chuck Norris does not sleep. He waits.
• Chuck Norris cannot love, he can only kill.

Here’s a glimpse of “Chuck”:

We like the Honda Tuning Magazine Reader’s Ride section, and we encourage anyone with a Honda family product to put it up on the board.

This was a paid post. Thank you Honda Tuning Magazine!

Ipod Shuffle Blog Contest

I just found out that Brandon Hopkins is having a contest for an iPod shuffle. All you have to do is link to him and link to this site about free business cards and you

Tundra Fuel Economy: 7 Ways To Improve your Tundra MPG

Yes — we know you bought a truck. You didn’t buy it to save gas. You bought it to do stuff. We get it.

But what if there was a way to do stuff with your truck and save gas? Interested? We thought so. Here are some tips.

1) Drive like your grandmother.

Your truck burns fuel at almost twice the normal rate during hard acceleration. If you’re racing from every stop light, you’re going to burn through fuel faster than green grass thru a goose. The ideal acceleration rate for maximum fuel economy is generally agreed upon to be about 2mph per second. At that rate, it would take you 30 seconds to reach 60mph. While we don’t really believe anyone can accelerate that slowly without getting shot at (or at least flipped off), if you don’t like your gas mileage try counting to 10 or 15 seconds as you accelerate. If you’re getting to your speed any faster than 10 seconds, you’re burning more fuel than you need to.

2) Avoid high speeds.

Believe it or not, aerodynamic drag, or wind resistance, isn’t significant until you’re traveling at 40-45mph. Then, as your speed increases, aerodynamic drag starts to build up rapidly. By the time you hit 100mph, your engine is working almost entirely just to overcome aerodynamic drag. In other words, less drag at low speeds means better fuel economy — that’s why your truck gets the best fuel economy at about 55mph. If you have to go faster, realize it’s hurting your efficiency.

3) Check your tires.

Other than wind resistance, the only other major friction you must fight is your Tundra’s tires. While the best fuel economy can be had using a highway tire with a car-like tread, you can actually get good results with a more aggressive off-road truck tire as long as the tire pressure is correct. Your owner’s manual will tell you what it should be for your specific vehicle, but it’s safe to say that 32-35 psi is a good safe pressure for just about any vehicle on the road. If it drops below 30psi, you’ll see your fuel economy take a hit. Also, don’t inflate your tires to the suggested pressure printed on the sidewall — that number is usually WAY too high.

4) Don’t drop your tailgate.

Here’s another believe it or not — dropping or removing your trucks tailgate *hurts* your fuel economy. The Canadian government sponsored a study — you can read it for yourself or just believe us when we tell you to leave your tailgate in the “locked, upright position”.

5) Stay up on normal maintenance.

Not that you shouldn’t be doing this anyways, but having a clean air cleaner, oil that’s been changed within the last 5,000 miles, and making sure your check engine light is off are all great ways to save fuel. Nuff said.

6) Look for excess weight you can remove.

Are you still hauling around tires or sandbags from last winter? What about all the “stuff” that’s in the back seat or pickup bed? None of it may seem significant, but a few items can quickly add up. Eliminating an extra 100 pounds of “junk” in your car can improve your fuel economy 1-2%. Not a lot, but every bit counts. Finally, consider telling your spouse to loose weight to help with fuel economy.

7) Make fewer trips that are longer in length.

Your engine doesn’t reach peak efficiency until it’s had enough time to warm up — typically about 15 minutes. If you can take all your short errands and string them together to form one super-errand, your engine will operate more efficiently during the majority of your trip.

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