More efficient new Ford F150: A shift from the old horsepower wars?
Ford released the official fuel economy label values for the 2015 aluminum-body Ford F150 this week and the general response from the media was disappointment. But Ford had much broader goals in mind when they switched to lightweight materials than just fuel economy. The 2015 F150 has impressive gains in hauling and towing capacity and acceleration, while still managing to exceed the typical fuel economy gains from reducing vehicle weight. In fact, the right question is not whether aluminum delivered the expected gains – it did – but why so much of the weight reduction was traded off for performance and hauling instead of fuel economy.
I blogged about the 2015 F150 pickup truck after it was unveiled by Ford at the January 2014 Detroit Auto Show, describing it as perhaps the most significant vehicle redesign in the last century. It is the first high-volume vehicle to use an aluminum body, but even more important it is in the vanguard of a truly radical transformation in designing vehicles using computer simulations and computer-assisted engineering.
Now that Ford has released all of the specifications for the 2015 F150, it is possible to make a proper assessment of the improvements from 2014 to 2015. While the fuel economy doesn’t quite match that of the Ram 1500 diesel engine – more on that later – “Ford bagged a key bragging right in the brutally competitive world of full-size trucks, announcing . . . that its all-new F-150 has best-in-class towing and payload capabilities,” as David Undercoffler put it in the L.A. Times. Despite eliminating the largest engine offered in 2014, the 6.2L V8, towing capacity increased to 12,200 pounds (3.5L V6 EcoBoost) and hauling capacity to 3,300 pounds (5.0L V8). Ford claims that this is 1110 pounds more towing capacity and 530 pounds more hauling capacity than for 2014. Reducing vehicle weight was the key to these increases in capacity.
What about that disappointment expressed to the fuel economy ratings? This can be evaluated using basic engineering principles. Weight, tire rolling resistance, aerodynamic drag, and accessory losses comprise the loads on the vehicle during operation. Of these, weight is the most important, as it impacts both the energy required for acceleration and tire rolling resistance, which is proportional to the weight on the tires. There have been numerous studies on the effect of weight on fuel economy since the first oil crisis in 1973 and the general rule of thumb is that a 10% reduction in weight improves fuel economy by 6-7% if the engine is downsized to maintain constant performance, or by 4-5% if the performance of the engine is not changed. Thus, the 14% weight reduction for the 2015 F150 should improve fuel economy by about 9.1% if constant performance is maintained and about 6.3% if the engine power is not changed.
The official fuel economy label values are rounded to the closest integer value. This rounding can introduce considerable variation in the comparison of 2015 to 2014 label values for the F150. To avoid this, I downloaded the 2014 and 2015 databases available from the www.fueleconomy.gov website, which contain unrounded values. The results for the combined fuel economy label value are as follows (where TC means turbocharged, i.e. Ford’s EcoBoost engines):
Of the four comparisons, only for the 2.7L Ecoboost has the engine been downsized for constant performance (in fact, even with the 2.7L, the power-to-weight of the 2015 F150 is a bit better than that of the 2014 3.5L EcoBoost). The fuel economy improvements of 18.3% (2wd) and 12.1% (4wd) are significantly better than the 9.1% improvement for a 14% weight reduction at constant performance.
The other three comparisons are between carryover engines (3.5L EcoBoost and 5.0L) or, in the case of the base naturally-aspirated V6 engine, the 2015 3.5L has slightly more power than the 2014 3.7L. Thus, the fuel economy improvements should be compared to a 14% weight reduction without reduction in engine power, or 6.3% increase in fuel economy. All of the cases exceed this rule of thumb except for the 2wd 5.0L.
It is important to understand that, because vehicle weight has been reduced by 14%, acceleration will be proportionally faster with the carryover engines, even though power output is relatively unchanged. Thus, in addition to the fuel economy improvements, the 2015 F150 will be substantially faster than the 2014 F150.
Even though Ford exceeded the rules of thumb for fuel economy improvements, it is clear that Ford made the change to aluminum as much to improve performance, if not more. Acceleration and towing and hauling capacity have all been substantially improved. It is the combination of improvements in fuel economy, acceleration, and capacities that is truly impressive – and will sell to pickup customers.
The disappointment expressed in the media that Ford did not do better on fuel economy is primarily due to viewing the fuel economy in isolation, without considering the performance improvements. This is exacerbated by unfair comparisons with the diesel engine in the Dodge full-size pickup truck. Yes, the diesel engine has higher fuel economy. But this ignores the fact that diesel fuel has 14% higher energy content per gallon than gasoline. The combined fuel economy rating for the Ram 1500 2wd diesel is 23.13 mpg, only 6.3% better than the 21.75 mpg for the 2.7L EcoBoost engine. Adjusting for the difference in fuel energy density, the F150 with the 2.7L EcoBoost engine uses about 7% less energy per mile than the Ram 1500 diesel. The RAM has higher label values only because of the higher energy density of diesel. This is supported by the CO2 emissions from each vehicle listed on fueleconomy.gov. The 2.7L Ford F150 emits 407 g/mile of CO2, 7% less than the 438 g/mile emitted by the Ram diesel. And, with the fifty cent to one dollar per gallon premium for diesel fuel over gasoline, the Ford pickups also cost much less to drive per mile.
A more interesting question is whether this is evidence that the vehicle fuel economy and CO2 efficiency standards are not significantly “biting” yet. Ford did adopt a novel strategy by reducing weight instead of the more classic “horsepower wars”, but the net result is still the same – much of the efficiency improvement was traded off to the performance and payload wars. Will adding towing and hauling capacity that most truck buyers didn’t know they “needed” lead to inflated expectations that might prove problematic a few years from now, when the manufacturers are supposed to meet even higher standards? That could be disappointing, although it is extremely likely that without efficiency standards, this performance war would be even more intense.
Attribute changes like this (namely increased towing and payload capacity) are especially problematic from a regulatory perspective for heavier-duty pickup trucks that comprise most of the commercial Class 2b/3 truck class. The efficiency standards for these medium-duty pickups, which are just across the regulatory threshold for light-duty vehicles based on gross vehicle weight, are directly indexed to payload and towing capacity. This provides an even stronger incentive for manufacturers to use lightweight technology in the medium duty commercial class to increase performance and capacity, as they will get less stringent fuel economy standards.
So the F150 story, in full, is pretty complicated. Ford has clearly done something very special technologically – and it is something to talk about. But whether this will be the game-changer that many expected in terms of increased efficiency is unclear as of yet. On the plus side are the aluminum breakthrough and reductions in fuel consumption and CO2 emissions. On the negative side are trading off much of the efficiency benefit for performance benefits and the risk of reducing the effectiveness of the medium-duty truck standards. Only time, and shifts in the sales-weighted average efficiency of Ford’s pickups compared with their competitors, will tell.