Safety and Fuel Economy Regulations Conspire To Reduce Truck Weight
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
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.
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