Safety and Fuel Economy Regulations Conspire To Reduce Truck Weight

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One of the easiest ways to improve fuel economy is to reduce vehicle weight. Estimates range, but it’s safe to say that a 10% reduction in vehicle weight can boost fuel economy at least 5%, and perhaps as much as 10%. Weight reduction is also desirable because, unlike other fancier technologies (i.e. direct injection, variable valve lift, hybrid-electric, etc.) it’s a relatively simple and inexpensive process. If you want to cut vehicle weight, you:

  • Find plastic you can replace with thinner plastic
  • Find lightweight metal you can replace with heavy duty plastic
  • Find steel you can replace with lighter metals

Simple, right?

OK – maybe not simple. Replacing a steel frame with a magnesium alloy (the most likely replacement material) means re-designing the entire vehicle…magnesium alloy is a different material with different assembly methods, so it’s not a matter of just swapping parts. Still, it’s less complicated to use alloys than it is to design fancy new engines, etc., which means that weight loss is a desirable method of fuel economy improvement.

Pickup Truck Weight Reduction

Reducing the weight of the average pickup truck will improve fuel economy, but will consumers like the side effects?

Because pickup trucks are heavier than the average vehicle, and because a 10% improvement in truck fuel economy represents a greater fuel savings than a 10% improvement in car fuel economy, it’s logical to conclude that trucks must lose weight. The trouble is, consumers don’t necessarily want lighter vehicles (truck owners especially).

First of all, replacing steel frames with magnesium alloy frames raises some long-term questions about durability. It’s certainly true that a magnesium frame can be designed to be every bit as strong as a steel frame, but are we sure that a magnesium frame will last as long? Magnesium-alloy is also much more difficult to repair than steel – what happens to a pickup that gets into an accident?

Magnesium alloys are also prone to ‘galvanic corrosion,’ which is caused when two dis-similar metals (like magnesium and aluminum) are exposed to one another in the presence of an electrolyte (i.e. salt water). Galvanic corrosion can reduce a hunk of magnesium to dust in a matter of weeks, so automakers must carefully coat or isolate parts to keep them for touching one another. If someone makes a mistake during design or assembly of a magnesium alloy frame, galvanic corrosion will make the 1st gen Tundra’s rusting frames look like a minor issue.

Of course, we can’t forget about cost. Redesigning a truck frame, and the building it from magnesium alloy (which is harder to work with) isn’t going to be cheaper – at least not in the short run. If automakers can improve truck fuel economy 10%, but they have to attach an extra $2000 to the sticker price to do it, are you on board?

Truck Weight Loss and Safety

In physics 101, we’re taught that force is equal to mass multiplied by acceleration (F=ma). In the real world, that means that heavier vehicles are safer than lighter ones…which is one of the reasons that so many people purchase pickup trucks or large SUVs. We all understand that being in a bigger vehicle is usually an advantage in an accident. However, if the average weight of a pickup truck is reduced, that safety advantage is reduced as well.

Amazingly, many safety advocates are seeking a reduction in the weight of the average truck or SUV because they believe it will help car owners survive more accidents. Lighter trucks represent a lesser danger to the average car owner, and therefore an industry-wide reduction in truck weight will help car owners (the majority of people on the road) survive more accidents.

While this certainly makes sense – and who isn’t for saving lives – lighter trucks increase the dangers to truck owners because lighter trucks are less stable. Lighter trucks are more likely to be steered by heavy loads, which could mean that truck owners are more likely to have an accident pulling a trailer with their new magnesium alloy framed pickup.

Still, when you come right down to it, there are two powerful forces conspiring to reduce the weight of the average pickup. If the fuel economy and safety advocates get their way, trucks will be lighter, more fuel efficient, more expensive, potentially less durable, and potentially less safe.

What do you think about that?

Filed Under: Auto News


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  1. Mickey says:

    How about doing 55 vice 70mph. That there will get me up to 22mpg. So I do 60mph and get over 20mpg. Not a hard concept to do. Not to mention when you lightened the Tundra under 7,000lbs then we don’t need to get the more expensive tags for a commercial truck. Some cities don’t allow commercial trucks on the roads. So it maybe cost effective with mpg’s and tags being less.

  2. Two things come to mind here.

    First, magnesium, as I recall, burns like living hell. It is impossible to put out and even burns under water. I think it takes some significant heat to ignite it but even so this raises a safety issue in my mind.

    Second, my personal experience and limited (unfinished) testing is that weight in the bed of the truck actually improves my fuel economy on the highway. Not so much in town stop light to stop light but on the highway it definitely helps. Not sure if it is related to momentum or if the truck is designed to run better with load.

    Fuel economy and trucks are words that seemingly do not belong in the same sentence but fuel economy is on everyone’s mind. Better MPG intentions are better served by better engines, transmissions, and even certain aerodynamic approaches but in my opinion making trucks lighter defeats the purpose of having a truck in the first place.

  3. Mickey says:

    Highway a good example of that magnesium burning is the British ship that was hit by a Argentine missile launch from an A4 in the Falklan war. The whole superstructure burned down. Like you said it was too hot and water isn’t what you can use to put it out. Water would pop and explode. You have to use sand to cool it down to put it out. Class “D” (delta) fire.

  4. mk says:

    can’t remember where I read it, but the trucks of the 90’s and even the 80’s were much lighter than the current full size trucks. I find this very odd and almost unbelievable, but it is true, at least with chevy trucks I am familiar with since those were always full sized as compared to the smaller pre-2007 tundras being 3/4 sized, not full sized in my opinion. All these fancy safety and techy features nowadays I do not want are killing the weight factor of our 1/2 ton trucks. Heck, toyota cannot make the sheet metal any thinner on our tundras I do know that, so please do NOT make the sheet metal plastic for god sakes.

  5. Jason (Admin) says:

    Mickey – A lower national speed limit would definitely improve fuel economy across the board (http://news.consumerreports.or.....-too-.html), but it’s an incredibly unpopular idea. Still, it would work, and I guess I would be on board if it meant reducing oil imports.

    Toby – I’ve read that the magnesium frames would be made from a fire-proof alloy, but who knows. You are correct that a magnesium frame (non-alloy) would be a fire hazard.

    As for adding weight to improve fuel economy, I think that your experience is unique. Still, I think you’re right: Lighter trucks really aren’t good for full-size truck owners in an of themselves. However, like mk said, lightening trucks by making them less complex would be fine with me.

    Mickey – Amazing! Didn’t know about that – just read up on it. Knew about the Falklands but didn’t know magnesium played a role.

    mk – You read it here! 🙂

    You might have read it somewhere else too…LOL.

    I don’t see Toyota going with plastic body panels, but aluminum and/or magnesium allow is likely. Many manufacturers use aluminum or magnesium alloys in vehicle hoods.

  6. Mickey says:

    Yes Jason being retired Navy. Had to know what will make you jump over the side for an unintentional swim.

  7. Jason (Admin) says:

    Mickey – LOL – makes sense.

  8. Danny says:

    here’s a thought but lets put a lil data out there 1st. my extended cab 1995 gmc z71 was about 1000 pounds lighter than my 2010 4×4 dc tundra. it has 110 less horsepower and averaged 17.75 mpg at 74mph on trips longer than 100 miles. My tundra averages 19 mpg at 70mph. so if you increase the tundra’s average speed to match the gmc’s, the mpg are about the same, more or less. now here’s the kicker, the mpg for the gmc is from pure gasoline and the tundra’s mpg are from 10% ethanol, so if fuels were the same, it should be safe to say that the tundra would get getter mileage. so, technology and efficiency has played a pivotal role here, and yes, decreasing weight would have made an improvement too, but how about making a more efficient fuel to go along with a more efficient vehicle. they are making more efficient vehicles everyday, but when they mandated ethanol, efficiency went out the window in an effort to be green. Also, does the extra fuel consumed and the extra carbon emmissions produced to go the same distance not offset the carbon emmissions saved buy using ethanol? oh, the numbers of 74 and 70 mpg is just where i happen to set my cruise control. if i dont drive in excess if 66 mph on trips greater than 100 miles, i average 20.5 mpg, actual mileage not the computer read out figures. just a thought!

  9. Leaveb3sbehind says:

    Another though, when I go to class during the daytime I average around 14.7mpg, At night on the way home I drive 5-10 over the posted hidiously slow speed of 35 and I catch nearly every light, I get 20-21 mpg. Why don’t we adjust lights and the speed limit in our cities first before mandating more garbage?

  10. Jason (Admin) says:

    Danny – I think your point about carbon emissions and ethanol is a good one. A lot of people argue that ethanol isn’t any better for the environment than gasoline.

    Leaveb3sbehind – An excellent point. I’ve seen data that shows the average pickup truck would get 25 mpg (or more) if it traveled at less than 40mph. That’s a huge improvement…and lower speeds would be safer too. I’m not sure that it would be a bad thing for all of us to drive a little slower.

  11. David Shores says:

    I believe that steel brackets can be replaced with strong aluminum in multiple places to include the rear seat brackets and front seats frames and brackets in the engine compartment. Lighter rims and brake systems should come factory stock without compromising performance. Lighter batteries while still providing reliability combined with LED’s in all the light systems. LED’s are lighter while using less electricity, last longer, and are lighter. Why are tailgates still so heavy? The technology exists to produce strong tailgates while also being lighter. Suspension systems can be lightened as well. Dropping the weight of the truck, both unsprung and dead weight, will improve gas mileage without compromising safety. It’s not a question of who wants it but the fact that it needs to be done. Towing capacities will not go down with a 200 to 300 lb weight reduction. Brakes, engine, the frame, and transmissions effect towing capacity. Toyota Tundras are behind on mpg. Why? Because while others have new engines and 8 and 9 speed transmissions, Tundras have stayed at a measly 14 mpg combined (real world mpg number) with standard 6 speeds. Everybody other truck is changing for the better and makes 22 mpg + on the highway. Why is the Tundra not improving? Why can’t the Tundra engines have the cylinder deactivation technology? Proven engines. I’m not saying that you need to redesign the engine. Try a 8 speed transmission on the same engines and lighten the truck while keeping the same appearance. These changes would be huge. I love my Tundra. I just wish Toyota would make these changes to keep me a loyal customer.

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