Challenge X

The teams in Challenge X employed many novel ideas, approaches, and technologies that (1) provided near-term and long-term solutions to significantly reduce well-to-wheel energy consumption, (2) reduce petroleum energy consumption and emissions, (3) significantly reduce criteria tailpipe and GHG emissions, and (4) increase pump-to-wheel fuel economy. All of the teams selected hybrid vehicle designs for their student-modified vehicles, spanning the gamut of parallel, through-the-road, and series hybrid electric vehicle. These vehicles employed state-of-the-art nickel metal-hydride and lithium-ion battery packs. A variety of advanced electric drive systems employed by the teams enabled the hybrid electric vehicle features, such as regenerative braking, high-load electric assist, and engine transient smoothing.

Engine selections were dominated by highly efficient diesels and turbocharged spark-ignited engines operating on biofuels such as ethanol and biodiesel. More advanced engines, such as highly diluted and boosted spark-ignition engines and hydrogen-assisted ultra-lean burn combustion strategies were also used.


  • Five teams included the use of hydrogen as a second fuel.
  • The University of California at Davis was the only team to use plug-in hybrid technology for the energy source for its Challenge X vehicle.
  • One team, the University of Waterloo, employed a fuel cell as its primary propulsion system.
  • West Virginia University and the University of Akron used ultracapacitors to source high levels of power for short periods of time and recapture energy from braking.
  • Several teams used the auxiliary power units from fuel cells to power air conditioning and other parasitic loads to aid in HEV propulsion.
  • Mississippi State University had a 48% improvement in fuel economy in Year Two.
  • Five teams, including Ohio State University and Virginia Tech, used belt alternator/starter technology for an electric performance assist in their vehicles.
  • University of Waterloo posted zero emissions in Year Four.
  • Utilizing Argonne National Laboratory’s GREET model, University of Wisconsin-Madison team demonstrated a 52% reduction in GHG emissions relative to production counterpart in 2007.
  • In Year Two, Virginia Tech achieved the lowest well-to-wheel petroleum energy usage, reducing its vehicle’s petroleum use by 77%.
  • Fourteen of the 17 vehicles were able to reduce greenhouse gas emissions in Year Two.
  • In Year Three, Penn State achieved 0.06 g/mi NOx emissions utilizing a downsized diesel engine and a Urea injection system (< Tier 2 Bin 5).
  • In 2008, Mississippi State University’s ¼ mile acceleration time was 1.6 seconds less than the production vehicle.
  • University of Waterloo competed successfully in every event as a fully functional fuel cell vehicle – a first for a fuel cell vehicle in advanced technology vehicle competitions.
  • The first ‘Outstanding Women in Engineering’ award was introduced in 2006.
  • University of Tulsa decreased well-to-wheel greenhouse gases by 41% in 2008.
  • 15 vehicles completed the 328 mile Road Rally in Year Four.
  • During the final year, Texas Tech achieved a 74% reduction in Petroleum Energy Use
  • The University of Texas at Austin was one of the first teams to include MP3 and GPS connectivity into their student-designed vehicle in 2008.