How Full Size Pickup Trucks Ride the Fence Between Cafe & Customer Wants

By on February 2, 2019 in DESIGN/MODELING/SIMULATION

The Big Three is turning to creative engineering solutions to meet demands.

The popularity of the highly profitable and highly popular full-size pickup trucks in the U.S. market creates an interesting dichotomy for automakers. Customers want improved payload, towing capacity and fuel economy. Automakers want to give customers all three, but they must meet governmentmandated NHTSA and EPA Corporate Average Fuel Economy (CAFE) and greenhouse gas (GHG) emissions regulations in ground vehicles.

All automakers selling in the United States must meet their fleet’s average fuel-economy numbers or pay the penalty for exceeding the standards. Here we examine some of the ways the Detroit Three brands, namely General Motors (GM), Ford and Fiat Chrysler Automobiles (FCA), attempt to balance federal requirements with customer requirements and why it is so important particularly for full-size pickup trucks. With automated, connected, electrified and shared (ACES) vehicles fast approaching reality, it is quite likely that some of the technology developed for these trucks will make their way into ACES vehicles.

Sales data shows that the market share of pickup trucks has grown along with crossovers (CUV), over sedans. (See Image 1.) The buying trend is indicative that pickup truck customers value superior durability, roominess, payload capacity and towing capability along with fuel economy. This customer preference creates a challenging optimization problem for the automakers who sell a large number of pickup trucks.

The market data shows that GM, Ford and FCA sell far more pickup trucks as a percentage of their total sales compared to Toyota and Nissan. (See Image 2.) Therefore, CAFE is highly affected by the fuel economy of pickup trucks for the Detroit Three automakers. Since trucks as a percentage of total sales are much lower for the Japanese brands, their standards depend more on sedans. As a result of this, this paper will focus on lightweighting the high-volume U.S. fullsize pickup market. For comparison, we used the highest body style in sales volume, which is the crew cab.

Pickup truck customers generally compare vehicles on payload and towing capacity (bigger is better), which require vehicles to be larger and have a more powerful propulsion system. A study by Resources for the Future (RFF) suggests that consumers would pay $134 for a 1-percent fuel economy increase. Alternatively, holding weight and marginal costs constant, the manufacturer could increase performance by 3 to 6 percent (depending on the market segment) rather than increasing fuel economy by 1 percent.

Pickup truck customers generally compare vehicles on payload and towing capacity (bigger is better), which require vehicles to be larger and have a more powerful propulsion system.

RFF estimates suggest that consumers would pay about $394 for the performance increase, far exceeding the value of the fuel-economy increase. The RFF report states, “Consumers would value vehicles more if automakers use fuel-saving technology to raise performance rather than fuel economy.”1 The dichotomy is that these customer desires are at the cost of worsening fuel economy, which the Detroit Three must continue to improve with a lot of creative engineering solutions.

Let us examine how the Detroit Three achieve their goals of improving the overall fuel economy of their pickup trucks while maintaining payload and towing capacities.

Lightweighting
Lightweighting is an important tool for optimizing fuel economy, as well as improving overall performance. Simply put, less mass needs less energy to move. Reducing a vehicle’s weight by just 10 percent can improve the fuel economy by 6 to 8 percent.2

Each of the Detroit Three automakers has invested heavily in lightweighting pickup trucks, and the results are irrefutable. (See Image 3, Table 1.) However, each of them has taken a different route to achieve the same objective.

With Ford’s previous experience with the aluminum-intensive vehicle program in the mid-1980s and the Jaguar production experience, the F-150 team lightweighted the truck by more than 700 pounds (curb weight). The frame remained high-strength steel, but Ford achieved this by using an all-aluminum body. This effort not only increased fuel efficiency, but also improved many other performance characteristics. Ford used the experience to lightweight the Super Duty pickup truck and the Expedition/ Navigator SUV.

General Motors approached lightweighting their full-size trucks differently. GM selected a mixed-material solution with steel for their body structure and used aluminum only for closures or hang-on panels, which do not contribute to the body structural stiffness. Extensive use of the latest ultra high-strength steel alloys resulted in significant weight savings for the GM Silverado without adding the degree of manufacturing difficulty imposed by an all-aluminum Body-in-White.

The 2019 Silverado is about 450 pounds lighter (curb weight) than the previous model. Although GM sells their trucks under two names, the Chevy Silverado and the GMC Sierra, for simplicity, we have used the higher-volume Silverado for our comparison.

FCA has taken a similar approach to lightweighting as GM, but to a lesser degree. Maintaining their all-steel body structure, they increased the use of high-strength steels. They have used sheet aluminum for their tailgates and hoods. With judicious application of high-strength steel for their structure and frame, as well as aluminum for selected closures, FCA has reduced their average weight by 225 pounds.

Propulsion (Powertrain)
While lightweighting is important, automakers benefit most by improving propulsion. A greater advertising focus is put on engine size, number of cylinders, turbocharging, horsepower and torque than other features. Engine size, as well, continues to go down even when the engine configuration may remain the same. (See Image 4.)

Similar to lightweighting, automakers employ different propulsion/ powertrain strategies to achieve performance and improve fuel economy. Common routes include engine downsizing, turbocharging, engine-tuning modes and advanced fuel management.

Ford introduced their EcoBoost turbocharged V6 engines that outperformed their V8 engines with breakthroughs in technology, thus improving horsepower, torque and fuel economy simultaneously. The primary direction for improving fuel efficiency has been to downsize the engine and add turbochargers to boost the output.

GM, on the other hand, has kept their engine lineup down to fewer choices with two of them being V8s. With the Active Fuel Management system, GM can achieve the desired fuel efficiency and not add turbochargers with their associated parts and complexity. The company has recently introduced a four-cylinder turbocharged engine in a full-size pickup truck.

FCA has also reduced their engine lineup to essentially two engines, a small V6 or the “Hemi” V8. However, the V8 is available as a mild-hybrid engine with an electric-motor torque assist and regenerative braking systems. FCA has dropped the diesel engine from their lineup for the 2019 model year.

With all the technology in this highly competitive truck market, what are the measurable effects of lightweighting and efficient propulsion? To find out, let’s compare the performance of each truck’s current generation with its previous generation.

Since trucks vary vastly in configurations, such as cab type, bed length and drive type (two- versus four-wheel drive), we can only look at baseline trim weights for each truck. We have chosen the crew cab, short bed, 4×2 truck configuration for comparison.

See Image 5 for the top three selling mass-market trucks’ reduced curb weight.

Similar to lightweighting, automakers employ different propulsion/powertrain strategies to achieve performance and improve fuel economy.

One of the benefits of weight reduction is improved payload capacity. (See Image 6.) The lower the vehicle weight, the higher the payload since the total weight or gross vehicle weight rating (GVWR) is the sum of the two. Several other factors, such as the number of speeds in their transmissions, final drive ratios and torque curves along with increased durability, will affect the load-carrying capability of trucks.

Another key benefit of improving overall efficiency for trucks is improved trailer-towing capability. Towing is one of the reasons customers prefer a truck over a passenger car. All automakers have very competitive trailer-towing capability. (See Image 7.) However, Ford and GM are leading the pack with properly optioned trucks towing more than 12,000 pounds.

Even if truck customers tow their trailers or boats only occasionally, knowing that they can when they want to seems to be important to them. Towing is one area where trade-offs with fuel economy are necessary to balance with total weight, engine power and engine/transmission cooling.

While fuel economy may not seem to matter as much as payload and towing capacity to pickup truck customers, it is one of many considerations for pickup truck buyers. It is also common knowledge that Ford, GM and FCA depend largely on trucks for their profitability. Therefore, maintaining high levels of fuel economy while maximizing payload and towing capacity is paramount for them. With every significant change or a completely redesigned model, the overall fuel economy has improved. (See Image 8.)

How can we utilize these lightweighting techniques in other types of mobility products as we move into automated, connected, electrified and shared vehicles? Some crossover vehicles or CUVs are already using technologies developed for full-size trucks for design optimization. These lightweighting and propulsion technologies have resulted in CUVs that approach sedans for fuel economy.

It would be interesting and valuable to explore how automakers have implemented advances in body structures, powertrain and aerodynamics to improve fuel-efficiency performance. Also, with the impending growth in automated, connected, electrified and shared vehicle technology becoming a competitive edge for automakers, the pressures to reduce overall weight to accommodate these new technologies will only escalate over the next decade. Similarly, improving propulsion and aerodynamic efficiency will, as well, continue to be pursued by all automakers for similar reasons.

Authored by Abhay (Abe) Vadhavkar 

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