2023 Ford F-150 Lightning XLT Yearlong Review: AeroX Fastback Roof Road-Trip Range Results Are In
Well, these results were unexpected. Can we trust them?
We promisedMotorTrendRoad-Trip Range test results for our Detroit-based yearlong 2023 Ford F-150 Lightning XLT test truck with the AeroX cap from Michigan Vehicle Solutions mounted on the back, and in this update we'll share them—along with a healthy dose of qualification.
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First a recap of the procedure: All testing for this exercise was done on the 4.71-mile-long oval track at the Stellantis Proving Ground near Chelsea, Michigan. Battery state of charge is noted at the beginning of each five-lap run, with sessions repeated at constant speeds of 55, 60, 65, 70, 75, and 80 mph. After each session, the battery SoC was noted, the truck was connected to a DC fast charger and recharged to precisely the same state of charge at which the session started, logging the kWh dispensed as well as the ambient temperature at the start and end of the test, and the actual distance traveled as reported by our Vbox GPS data logger.
Real-World Range Results
The initial test with just the tonneau cover in place occurred on a clear spring day with temperatures ranging from 65 to 80 degrees F. The AeroX test occurred on a similarly clear fall day in nearly identical temperature conditions ranging from 64 to 80 degrees. Even the wind conditions were the same, per wunderground.com—southwesterly, 5-10 mph gusting to 15—and in any case, we reckoned any wind effects should be cancelled out by spending as much time driving into and away from any wind that hit the oval.
Our AeroX test session started with the optional spoiler attached, running our standard 70 mph speed. That configuration returned a 1.74 mi/kWh consumption figure and a 213-mileMTRoad-Trip Range—both 11 percent worse than the baseline tonneau cover condition. We then removed the spoiler and restarted the the 70-mph test. Consumption improved to 1.89 mi/kWh and range to 231 miles, but these figures still represented a disappointing 3.6 percentdegradationin range, relative to the tonneau-only condition at 70 mph. Sadly, these results would be echoed at every speed except 80 mph, when the AeroX appeared to cut consumption by 1.3 percent and boost range by 1 percent (to 196 miles, up from 194).
How Can This Be?
We reached out to AirShaper's Wouter Remmerie immediately, sharing photos of the AeroX cap and asking if he could spot any major differences between it and his original idealized fastback cap. He expressed concerns about the gap between the cab and cap possibly inducing turbulence, ditto the cab's antenna protrusions, and the substantial inset of the rear window within the hatch frame. He then graciously offered to run our cap through his simulator, mounted to a 3D-scanned "digital twin" of our F-150 Lightning—providing there was a 3D model of the AeroX cap. There was not.
IPF Racing to the 3D-Modeling Rescue
MVS built the AeroX from a styling buck with no CAD files. One option for generating a file we could run through AirShaper's online platform would've been to enlist the very same global benchmarking organization that generated the Lightning's digital twin we'd be using: A2MAC1 (see "Who Is A2MAC1?" below). We could have waited for an appointment to bring the truck and cap into A2MAC1's Belleville, Michigan, facility for measurement, but we chose an option that was quicker and more accessible: an independent scanner. We rang up IPF Racing founder Zac Watts, who had recently 3D-modeled a Cadillac Cimarron wheel for a buddy of ours (Detroit's rife with wacky projects like this, and IPF Racing has the gear to not only scan, but also 3D-print or CNC-machine many of them). Watts brought over his Shining 3D EinScan HX scanner, selecting its blue-laser function, which is best for flat panels (it also supports structured white light, which is better for engine-bay scans).
He started by sticking tiny reflective dots randomly all over the surface of the cap. Next, he sprayed the surface with a self-evaporating dulling spray. Then he calibrated the scanner to the ambient light inMotorTrend's Detroit garage and set about systematically scanning the entire surface with his light gun. We watched the surface come to life on his computer screen, gradually building a model that would eventually comprise 16.5 million points. Cleaning up the model for use by any of the popular modeling formats (STL, STP, IGES) took another couple days. After the scanning, we removed all the dots, wiped the remaining dulling spray off, and prepared the AeroX for real-world testing.
Real-World Aero Testing
While waiting to run a proper 3D-model analysis, we decided to employ old-school real-world aero testing using yarn tufts to quickly assess some of Wouter's primary concerns. This is wind-testing anyone can afford. Simply buy some yarn in a contrasting color, wrap a bunch of it around your four fingers, cutting through the winding to produce a bunch of yarn telltales the same length, and then tape them all over the aerodynamic surface you're looking to study. We did just that, placing the tufts in an orderly pattern all over the back half of the cab and the cap. We then mounted GoPro cameras with fisheye lenses capable of observing most of the cap and took still photos of the truck driving at 45 mph on arrow-straight Woodward Avenue. With gray gaffer's tape, we were able to eliminate the gap between cab and cap, to gauge whether that dramatically reduced the turbulence.
Initial Results
Airflow over the cab and onto the cap appeared to be attached and laminar, as attested to by yarns calmly pointing aft, in both the open-gap and taped configurations. But agitated and backward-blowing yarn tufts on the rear glass, especially near the top, indicated flow separation and turbulence.
On the sides of the cap Remmerie noted remarkably nervous flow with a strong upward component. A combination of turbulent flow set up by the mirrors and exacerbated by the cab-to-cap gap likely accounts for the nervousness, while a low-pressure area on the rear glass draws the air upward and inward.
Does AeroX Work or Not?
In early chats with Remmerie and representatives of A2MAC1, the benchmarking specialists whose digital model of the Ford F-150 Lightning we'll be mounting our IPF Racing model, we learned there are numerous potential pitfalls to real-world testing on an oval track—the most concerning of these for this exercise is yaw. According to Vincent Keromnes, A2MAC1 technology and performance insights product director, the average yaw angle when crossing from one straight to another on an oval is 4 degrees. Wind hitting the truck at that angle (or more) encounters a far greater frontal area with the AeroX cap than it does with just the tonneau cover. This could potentially explain our results. But we'll reserve final judgment on the AeroX cap's aerodynamics until we get the official simulation results from AirShaper and A2MAC1.
Who Is A2MAC1?
A2MAC1 is a global competitive benchmarking leader with a proprietary system for developing "digital twins" of any vehicles. The process begins by sourcing a vehicle from a dealership, which is then sent to one of A2MAC1's five benchmarking centers globally. There it is dismantled and analyzed in a systematic process, with each single component being scanned—including the body-in-white sheetmetal. These models are then rebuilt as a digital mock-up, with the comprehensive files made available to all automotive OEMs and suppliers via a subscription to its database. The company's database includes more than 2,550 vehicles from around the globe; including measurements, 3D models, material data, and the vehicle's bottom-up cost and CO2 impact, as well as supply chain insights that the company says can help automotive industry players realize continuous product optimization, profitability, and sustainability improvements.
For More on Our Long-Term 2023 Ford F-150 Lightning XLT:
- Off to a Bumpy Start
- Navigating Midwest Charging
- Forestry Service
- Range Strategies
- Offroad Adventure
- Understanding Range Prediction White Lies
- We Gave Our Ford F-150 Lightning a Fastback Roof
- The Coolest EV Range-Extending Tech at CES 2024
Photos Contribution by Steve Pham
I started critiquing cars at age 5 by bumming rides home from church in other parishioners’ new cars. At 16 I started running parts for an Oldsmobile dealership and got hooked on the car biz. Engineering seemed the best way to make a living in it, so with two mechanical engineering degrees I joined Chrysler to work on the Neon, LH cars, and 2nd-gen minivans. Then a friend mentioned an opening for a technical editor at another car magazine, and I did the car-biz equivalent of running off to join the circus. I loved that job too until the phone rang again with what turned out to be an even better opportunity with Motor Trend. It’s nearly impossible to imagine an even better job, but I still answer the phone…
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