More than half-a-century ago, way back when the first interstate highways were seeing travelers put the rubber to the road, a fleet would do well to average 4 to 5 miles-per-gallon (mpg) on their trucks. Today, that number has climbed to around 6.5 to 8 mpg.
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To the average onlooker, that may not seem like a huge improvement, but consider that the length of the trailer has increased by around 20 feet and we’ve added more weight – to the tune of around 7,000 pounds.
This time has also seen us change tires (bias ply to radial) and engines (naturally aspirated to turbo charged). Now we are seeing the adoption of electronically controlled diesel engines.
To compound the issue more, road speeds have increased. Fifty years ago, 40 or 50 highway miles-per-hour (mph) were normal. Today our road speeds have jumped to somewhere between 55 and 70.
The Inside Story
In short, heavy-truck manufacturers have doubled fuel efficiency while not compromising on strength. Indeed, they have even built on their engines’ strengths, creating a more powerful product that uses less fuel.
So while we have made great progress in doubling our fuel economy while not compromising on our engine performance, don’t expect the jump from 8 mpg to 10 mpg to be as quick and painless as the jump from 4 to 8 was. Today, greater fuel efficiency gains are coming more in small steps than they are in great leaps. But why?
The fact is, a fleet that can claim 8 mpg today is doing pretty darn well. These are the fleets that are adopting the latest technologies and techniques early on. You would be hard pressed to say that a full half of the fleets in operation out there are running at 8 mpg, but the fact that many large carriers are at the top end balances out the numbers.
There are fleets out there that can lay claim to 10 mpg under certain conditions, although they aren’t the norm, nor can they say they are averaging 10 mpg across their entire fleet. National fuel economy averages often come in around 6.5 – 7 mpg, so getting 10 mpg from them would be quite the task.
Following the S-Curve
To get a full understanding of what a jump to 10 mpg would require, consider that trucking technologies evolve on an S-curve. Where the potential of their impact increases over time, a short jump is followed by the leading edge of a plateau.
Although aerodynamic improvements have been finding wide adoption, from trailer side skirts to boat tails and the integration of the two, there’s only so much air you can displace. At some point the basic technologies underpinning modern big rig design will have to change.
Most of the dramatic improvements have already been invented and implemented. Most of what we can do will be incremental, at least until major new inventions upend the market.
And even the inventions we have come to expect come with their own costs. To achieve major gains, aerodynamic accessories must be manufactured with lightweight alloys, which in turn raises their cost. When it comes to fuel efficiency, there’s no free ride.
Paying the Price
In the end, the vital question is how much the industry is prepared to spend on acquisition prices for major new technologies. As we’ve reported, some of these news super trucks being tested have seriously advanced technologies, such as waste heat recovery.
If demand for diesel drops and prices fall, you can also expect the adoption of these new technologies to stall out. It’s likely that in 2008 no one could have predicted that diesel prices would be where they are today.
Furthermore, what if we see a day where electric or natural gas powered vehicles take over as the most viable options. It’s hard to bank on oil savings efficiency if you might not even need to worry about it down the road.
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Of course, this is a complicated topic. Fleets have a lot more incentive to increase their efficiency than just meeting a standard. Their bottom line is at stake.