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The Teams Competing in the Automotive X Prize have the same Destination — Building a Car that can get 100 Miles per Gallon. But no two Teams Agree on the Best Path to that Goal.

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Associate Editor

Mechanical Engineering 132(10), 38-40 (Oct 01, 2010) (3 pages) doi:10.1115/1.2010-Oct-4


This chapter explores experiments conducted by different automotive engineering teams competing in the Automotive X Prize to design a car that can get 100 miles per gallon. The performance goals the X Prize Foundation laid out are so specific that they could have a positive effect on the entire high-efficiency segment of the automotive industry. Unlike a lot of the cars entered in the X Prize, the Tango is a production vehicle, though the runs are small. Tango is one of the heavier cars in the competition. It is also solidly built with a race car-style roll cage protecting the driver. The car, entered by Edison2 of Lynchburg, Va., is quite narrow, however, instead of tucking its wheels inside, the footprint mounted them on posts that extend away from the body, or fuselage. The vehicles had some performance standards to meet, and each one would be taken to Argonne National Laboratory in Illinois to undergo rigorous emissions testing. The biggest effect the Automotive X Prize competition may have is providing a new set of benchmarks for car designers to meet.


When the cars entered in the Progressive Insurance Automotive X Prize competition assemble on the same track, it looks like no race most of us have seen. With Formula 1 or NASCAR or the Indianapolis 500, there is a basic similarity to all the entrants. Part of that is due to competition rules (indeed, the IndyCar circuit requires all cars to use a body supplied by the same company) and part is due to engineers and car designers all reaching the same conclusions independently.

Conversely, the cars at the starting line at the Michigan International Speedway in Brooklyn, about 50 miles west of Detroit, couldn’t be more different from one another. The goal the cars are striving for is the same—to average 100 miles per gallon while meeting a number of other performance marks—but the designers on each team found radically different approaches to reach it. The cars use different types of engines—or no engines at all. Some are derived from standard automobile bodies while others look more like race cars or experimental aircraft. Not all have four wheels.

Most teams fell short: Out of 26 entries, only 15 made it to the final stages. But the almost blank slate that the designers had to work from freed them to come up with some incredibly innovative ideas. And while it’s too soon to know how much influence the Automotive X Prize will have on the commercial car market, where consumer preference can force automakers to hew toward the traditional, it is surprising to see just how many ways there are to make a hyper-efficient automobile.

THE AUTOMÛTIVEXPRIZE WAS ESTABLISHED IN 2007 TO SPUR THE DEVELOPMENT OF HiGH-EFFiCIENCY VEHICLES, The X Prize Foundation set up a $10 million prize pool (Progressive Insurance signed on later as a title sponsor) to reward teams that could present a car that achieves the equivalent of at least 100 miles per gallon of gasoline, emits less than 200 grams of carbon dioxide per mile (taking into account the full well-to-wheels fuel cycle) and meets EPA standards for other emissions. In the event that more than one team made the grade, there would be a race to determine the winner. To claim the prize, the cars would also have to meet a minimum safety standard and the company would have to have a plausible business plan for achieving mass production.

The performance goals the X Prize Foundation laid out were so specific that they could have a positive effect on the entire high-efficiency segment of the automotive industry, said Eric Leonhardt, director of the Vehicle Research Institute at Western Washington University in Bellingham and the leader of one of the teams in the competition.

“It’s been exciting to have to meet such a high bar,” Leonhardt said. “We’ve all heard claims from manufacturers, and it’s been frustrating to me because I know that people driving down the road aren’t getting the fuel economy that’s claimed. That’s not good for the industry. Fiaving a comparison using the same benchmarks is important.”

Although the hope had been for mass manufacturers to enter their leading-edge cars in the competition, Chevrolet decided against submitting its new hybrid Volt and Honda didn’t enter its battery-powered Leaf. By the time the contest started earlier this year, the only mass manufacturer to compete was the Indian carmaker Tata, which entered its Indica Vista EV X.

All told, 21 companies brought cars to the Michigan International Speedway in April to begin a shakedown phase, which focused on safety inspections. A knockout phase in June, which was oriented toward efficiency, emissions, and a hill climb, eliminated all but 15 cars from 12 teams. Surprisingly, there’s not a consistent design philosophy in the cars that remain.

FROM THE SIDE, THE TANGO LOOKS LIKE A CONVENTIONAL, IF VERY SMALL, SUB-COMPACT. There are Smart Fortwos parked on the streets of New York City today, for example, that have roughly the same profile.

It’s only as you walk around to the front of the Tango, built by Commuter Cars of Spokane, Wash., that the car’s main distinguishing feature becomes apparent. The Tango is only 39 inches wide. It looks as if it had been caught in a giant hydraulic press and squeezed, cartoon-like, to half the width of a normal car.

Unlike a lot of the cars entered in the X Prize, the Tango is a production vehicle, though the runs are small. Indeed, Commuter Cars is small enough that the company’s president, Rick Woodbury, is also its driver in the X Prize.

The basic design of the Tango dates back to long California commutes Woodbury put in back in the 1980s. Stuck in traffic, he realized that the basic problem was that every person driving himself alone to work takes up about 2,400 square feet of highway space, assuming three-second spacing at highway speeds. Reduce that space, he reasoned, and you can eliminate most or all of the traffic problem.

The Tango’s micro-size footprint doesn’t enable it to serve as a primary vehicle. Its battery power doesn’t allow for the range needed for a vacation drive, and the car can comfortably seat just two people, one in front of the other. But the Tango is designed for one job—a daily commute—and for that it seems more than adequate.

Woodbury calls the Tango “the fastest car you can drive in an urban situation.” The secret, he said, is the extraordinarily narrow width. In many localities—California being one of them—it’s legal for a motorcycle or a vehicle of similar width to run along the white line between traffic lanes. While gridlock may mire conventional cars, the Tango can keep moving.

“Driving the Tango through a standard Tuesday night traffic jam, I made it from the Beverly Center to downtown Beverly Hills—that’s 1.2 miles—in six minutes,” Woodbury said. “A regular car that left at the same time going as fast as he could took 15 minutes.”

Its stripped-down design also allows for incredibly fast acceleration. The Tango has been clocked going to 60 miles per hour from a standing start in just 4 seconds. Each of the electric motors on the rear wheels can deliver more than 1,000 foot-pounds of torque.

This performance is all the more surprising since the Tango is, at around 3,300 pounds, one of the heavier cars in the competition. It’s also solidly built, Woodbury said, with a race car-style roll cage protecting the driver. “But it’s small enough and quick enough that you ought to be able to avoid most collisions in the first place,” Woodbury said.

IF THE TANGO HAS THE ACCELERATION OF A DRAG RACER, THE VERY LIGHT CAR LOOKS SOMETHING LIKE A FQRMULA 1 CAR. The car, entered by Edison2 of Lynchburg, Va., is quite narrow (though not as extreme as the Tango), but instead of tucking its wheels inside that footprint, the chief of design, Ron Mathis, mounted them on posts that extend away from the body, or fuselage.

“We couldn’t make a basic rectangular car and get the kind of drag coefficient we needed,” Mathis said. “That leaves you with a body that’s not wide enough to fit the wheels in and still get good stability.” Mounting the wheels on pods at the end of long axle beams enabled the car to get good handling while retaining an aerodynamic shape.

Edison2 was founded by Oliver Kuttner, a real estate developer who has owned and operated racing teams in the past. Kuttner doesn’t see himself as a potential manufacturing mogul, however, and instead of putting together a car company, he has assembled a team of experts to work on the cars the way a Hollywood studio hires directors, actors, cinematographers, and other professionals on a movie-by-movie basis.

“It’s like a movie,” Kuttner said. “You get the real stars, but you only pay for them when you need them.”

Mathis, for instance, commutes down from his home in Indianapolis to work on the Very Light Car. A mechanical engineer who has spent a career designing race cars and working as a racing team engineer, Mathis was intrigued by the prospect of doing something that had the potential to make a long-lasting impact.

One of the first design decisions was to avoid batteries, fuel cells, and other exotic technologies to power the car. Instead, Mathis and his co-workers selected a motorcycle engine—a Yamaha WRX with a 250-cubic-centimeter displacement. The engine was modified and optimized to power a car. For instance, the design makes an unusually large use of exhaust gas recirculation, Mathis said. But the choice of such a small engine required the car to be as lightweight as possible. Every component of the car, from the suspension system and brakes down to the very nuts and bolts, was examined and redesigned to minimize mass.

The result is a car that weighs less than 750 pounds—not that much more than the batteries in the Tango. Coupled with a teardrop shape with a minuscule drag coefficient of 0.159—compared to around 0.3 for a standard car—it doesn’t take much power to get the car moving.

“We have a very fun car,” Kuttner said. “It’s quick, it stops, it turns—it’s definitely in sports car territory.”

That minimal shape dictated some design decisions. Protruding rearview mirrors, for instance, are replaced by cameras. And the wheels were placed on posts, which not only helped create a more aerodynamic shape, Mathis said, but could also lead to increased safety in the case of a collision.

The Very Light Car might be the vehicle of the future, but don’t expect any Edison2 dealerships to pop up. Kuttner says his goal is to develop a technology platform that can be sold to established manufacturers.

“We’re looking for government or industry support to take this car to the next level,” Kuttner said. “I know what we don’t know how to do, and we don’t know how to be a car company.”

NOT EVERY CAR THAT MADE IT INTO THE FINAL STAGES OF THE AUTOMOTIVE X PRIZE COMPETITION IS A PRODUCT OF THE PRIVATE SECTOR. The Viking 45, a slinky sports car, was built by students at the Vehicle Research Institute at Western Washington University.

Unlike some of its competitors, just about everything about the Viking 45 was selected to save money. For instance, while some vehicles are powered by bespoke engines or exotic electric motors, team leader Eric Leonhardt said the Viking 45 uses a three-cylinder engine pulled from a used Honda Insight.

“On a limited budget, this was an engine that could meet the requirements,” Leonhardt said. “We are capable of making our own engine, but to get one up to the level needed for the contest was beyond our time and budget parameters.”

The institute’s students have been putting together vehicles as part of the automotive design curriculum for nearly 40 years. Many of these have been focused on particular design criteria—economy, say, or the use of alternative fuel—so dealing with the arcane X Prize rule set was just par for the course.

Given the limit on improving the power train, the students looked to find other factors that they could influence to increase efficiency. One of the key innovations was the construction of a carbon composite monocoque chassis. The lightweight chassis helped keep the overall weight of the vehicle (including a driver) to 1,835 pounds.

“It’s very low to the ground and very aerodynamic,” Leonhardt said. “And thanks to the construction, it’s lighter than a Honda Insight.” But unlike some of the other cars in the competition, the Viking 45 doesn’t require a complete rethinking of what a car should look like.

One interesting aspect of the carbon composite chassis is that it requires a different skill set to manufacture than traditional steel frames. Indeed, if the technology caught on as a standard automobile feature, Leonhardt suggested, it might move the center of gravity of car making to a place like the Puget Sound region, which has composite expertise derived from its aerospace and marine industries.

In any event, Leonhardt wishes that more major car companies had tried to win the competition. “If we can do it,” he said, “they can certainly do it.”

AT PRESS TIME, THE COMPETING CARS STILL HAD HURDLES LEFT TO CLEAR. The vehicles had some performance standards to meet and each one would be taken to Argonne National Laboratory in Illinois to undergo rigorous emissions testing. The winners won’t be announced until this month.

There is, in fact, no guarantee that anyone will win. In that event, the prize money would roll over for another race to be held later. In late July, the Very Light Car completed a 200-mile range test at Michigan International Speedway with plenty of fuel left in the tank. Preliminary estimates put the fuel economy at around 120 miles per gallon, and the car looks set to win its class. The Tango was knocked out for failing to meet the fuel economy standard, and the Viking couldn’t pass the avoidance maneuver and 60-to-zero braking tests.

The biggest effect the Automotive X Prize competition may have is not so much in introducing a new, highefficiency car to the world, but as Leonhardt said, providing a new set of benchmarks for car designers to meet. Perhaps one day consumers will be able to go to an auto showroom and buy an X Prize class car—not just from the companies competing at the Michigan International Speedway, but from every manufacturer.

Copyright © 2010 by ASME
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