Hey, Soccer Moms: Drive These SUVs!
Challenge X shows that teams of college students really can make environmentally friendly sport utility vehicles that may appeal to everyday consumers
”Ummmm, who’s got that restart key?”
The speaker is a slightly worried Mike Wahlstrom, coteam leader for the University of Waterloo’s Challenge X team. The impetus for his question is your intrepid reporter, who has managed to stall the Canadian team’s unique, fuel-cell-powered Chevy Equinox. It won’t restart, and we’re blocking a traffic lane at midday in downtown Detroit.
The cause of the problem? My aggressive driving: mimicking any suburban commuter, I floored the accelerator as I pulled into oncoming traffic. Because one of the two electric motors was disabled, as Wahlstrom explained after we got the car restarted, the vehicle controller fed too much voltage into the remaining motor, whose control software triggered a shutdown to protect it from burning out.
Flooring a car isn’t unusual, though; drivers do it every day. And that challenge—making a highly modified SUV usable by everyday consumers—lay at the heart of the third year of Challenge X. It’s a competition funded by the U.S. Department of Energy and dozens of other sponsors, including General Motors Corp. GM donated brand-new 2005 Chevrolet Equinoxes to the 17 college teams, which each must attempt to build a sport-utility that uses less petroleum and emits fewer pollutants and greenhouse gases.
Following a full year of computer modeling, simulation, and design testing, the teams set to work with cutting torches in 2005. In last summer's event to end Year Two, their modified engineering prototypes—known by the industry as ”mules” for their often-balky behavior—were put to the test at GM’s Desert Proving Grounds in Mesa, Arizona.
The challenge for Year Three was to improve those mules to a ”99 percent acceptability level.” In English, that means making them something a soccer mom could drive—ideally without ever noticing the technology changes, except perhaps at the gas pump.
No Jerking, Shuddering or Noise, Please
My drive in the Waterloo vehicle followed another week of testing, this time at GM’s Milford Proving Ground, outside Detroit. The tests were modeled on the same challenges that any new production vehicle must meet: smooth and consistent drivability under all circumstances, without jerking, shuddering, or power-train noise; brakes that last through repeated hard stops from high speed; the ability to tow a trailer weighing 500 kilograms or more; air-conditioning that works flawlessly; ultrareliable accessories like electric windows and navigation system; high-quality interior trim and appointments; and so on.
Unlike last year, this summer the winning vehicles were pretty close to showroom-ready. Mississippi State University, the surprise come-from-behind victor over last year’s second-place University of Wisconsin-Madison team produced a vehicle so professional that it could easily have appeared on a dealer’s floor—assuming the multicolor paint job and 30 or so sponsor logos were removed. A neat cover shrouded its direct-injection 1.9-liter turbo diesel engine, and the batteries for its hybrid electric drive fit beneath the floor of the load bay, eliminating any compromise in load space. (The battery pack occupied the former spare-tire well, as all 17 teams were equipped with identical run-flat tires.) In fact, Mississippi managed to increase rear load space; they cleverly fitted updated, less intrusive interior panels from a 2007 Equinox. Their vehicle performed on the road, too, achieving a 48 percent reduction in fuel usage over the baseline unmodified 2005 Equinox.
But the competition was fierce, and the two top teams were separated by merely 7 points out of a possible 1000: Mississippi scored 895.5, Wisconsin 888.3. Last year’s winner, Virginia Tech got 809 points, only enough this year to take third. As Ohio State’s Eric ”Hot Shot” Schacht put it, ”Most of the teams finished most of the events, but that wasn’t enough—we found the level of competition unexpectedly high.”
Like any competition, this one had its share of mishaps. Virginia Tech broke a half-shaft during the trailer tow. A pipe ruptured in Michigan State’s unique hydraulic hybrid, making quite a mess on GM’s test track. And the Waterloo team persevered through a series of freak accidents that earned it other teams’ astounded sympathy. During the first day’s first inspection, a hydraulic lift malfunctioned and the vehicle slipped sideways, damaging an expensive custom-made carbon-fiber doorsill. Then, in on-road testing, the suction cup holding the tester’s accelerometer to the windshield failed—dropping the instrument directly onto the dash-top kill switch, cracking its housing and triggering a full shutdown of the batteries and fuel cell at speed.
Weight Loss and Plastic Surgery
But such events are a standard part of development. And it had been a busy year of modifications, with every team tweaking, replacing, improving, and refining dozens of components, major and minor. Michigan Technological University, for example, cut its estimated coefficient of drag from 0.42 to 0.36 by adding rear-wheel-well covers (or ”spats”) and modifying the front air dam, to cut fuel usage at high speed and reduce wind noise. Wisconsin reduced the number of cells in its battery from 44 to 40, letting it restore rear load volume to standard. Penn State cut 5 kg from each disc brake by creating titanium rotors mounted on aluminum hubs.
Waterloo shaved the weight of its very heavy—and heavily modified—fuel cell vehicle by using carbon fiber for the hood (dropping it from 23 to 8 kg), creating a new wiring harness with 22-gauge wire rather than 18-gauge (8 more kg), moving the voltage controller (eliminating 7 kg of heavy cable), and so on. The final vehicle weighed in at 2173 kg, merely 4 kg under the maximum 2177 kg.
And that year of refinement really brought results. In drive after drive, the mongrelized SUVs—most with new engines, hybrid-electric drive added, and a plethora of sophisticated new systems—ran almost like production vehicles. One giveaway was the six-speed manual transmission used by many: Few North American SUVs even offer manuals. Diesel clatter was another telltale, though some teams muffled it better than others, with Ohio State’s active-damping of engine vibrations winning it the lowest-noise prize.
For all the teams, said on-site organizer Steve Gurski of Argonne National Laboratory’s Transportation Technology R&D Center, which coordinates the event, the biggest engineering challenge proved to be ”mimicking GM’s high-speed LAN protocols” after replacing the engine and adding new components. He stressed the enormous time it took to ensure compatibility among the control modules for new, more complicated hardware (battery packs and one or more electric motors) whose components had to interact frequently to provide smooth operation under any conceivable driving pattern.
Wanted: More Time for Control Software
Every team’s wish list included more time to refine the control software. (Lithium-ion batteries, aluminum front and rear subframes, and better communication with offshore vendors filled out several lists.) Discussing both control software and the contest itself, Andrew Shabashevich from the University of California-Davis team said simply, ”It’s the largest learning curve I’ve ever had.”
Despite the setbacks, the long hours, and the less-than-perfect results, the teams were jubilant—and less exhausted and hollow-eyed than last year. In 2006, the challenge had been just to keep their vehicles running. This year, it was a true competition among well-matched foes.
The rewards were many. For Penn State’s Tim Cleary, ”The best part of the proving grounds week was being able to drive amazing cars, like a Cadillac XLR-V; that made all the late nights worthwhile.” For the Waterloo team, it was a personal visit from GM chairman Rick Wagoner, who even took their car for a spin. At 6 foot 5, (1.96 meters), he was a tight fit; they used lightweight racing seats to fit over the 36-centimeter-tall fuel cell that replaced the floor pan of their Equinox.
Almost 30 team members got a more tangible reward: a job offer from one of the contest sponsors. GM alone extended 12 offers this year during competition week.
A late surprise was the addition of a fourth year to the former three-year contest. Reinforcing the importance of consumer acceptance, the Challenge X entrants will go on the road and seek public feedback. Prizes are likely to go to teams whose vehicles are best rated by actual consumers along the way, and remain drivable and reliable over an 800- to 1600-kilometer road rally that will end in Washington, D.C.
Like the others, the Waterloo team is eager to show off its years of hard work. Last year it won the Spirit of the Contest award for choosing to use a fuel cell—more audacious in 2004 than it would be today, given GM’s announcement that it expects to market a fuel-cell car by 2015. This year, it got sixth place and a visit from GM’s chairman.
Even aggressive driving by a journalist couldn’t dampen the team’s élan. They’ll clearly have the second motor back in operation a year hence. So, would I buy their Equinox? Not yet. Among other concerns, it has no rear load space—that’s occupied by the hydrogen tank. But like the rest of the entrants, every team member has a future in auto engineering. And for a North American auto industry under siege, that makes Challenge X a bright beacon of hope for the future.
About the Author
John Voelcker is the automotive editor for IEEE Spectrum. He has also covered automotive technology in print, online, and on air for Wired , Popular Science , Portfolio.com, and various National Public Radio programs. Beyond auto journalism, he consults on business strategy and product development for interactive media.
General Motors Corp. paid for the author’s airfare between New York City and Detroit and for one night’s hotel stay, with Spectrum ’s prior approval.