When we were there, we saw this car in the parking lot. In addition to the picture of the field with the cannon, it says Wilson's Creek National Battlefield with the National Park Service logo, and under that, the label on the back of the car says "Clean Cities" (U.S. Department of Energy)
I found information on this on a NPS website (listed below)
Wilson's Creek Wraps Up Hybrid Technology
A partnership with the U.S. Department of Energy Clean Cities Program and Toyota Motor Sales has put a Toyota Prius? hybrid vehicle on the road at Wilson's Creek National Battlefield. The car will be used in the park and the Springfield, Missouri, area by interpretive rangers and other park staff. Driving the vehicle will help educate more than 200,000 annual visitors about hybrid technology and the NPS commitment to exploring innovative ways to better protect, manage, and preserve natural resources. Toyota Motor Sales donated the graphics "wrap" for the vehicle, which features images of the battlefield landscape complete with a cannon and rows of corn. Toyota also provided informational cards for visitors that explain hybrid technology and recognize the park's dedication to environmental stewardship and sustainability.









