This paper evaluates adaptive passive technologies for improving robotic locomotion in unstructured environments, focusing specifically on the Passively-Transformable Single-Part Wheel (PaTS-Wheel) and our novel variant, the “DogBone-Wheel.” We assessed these wheel designs in authentic woodland environments, measuring their energy efficiency, vibration profiles, and traversal capabilities in comparison to traditional wheels. Our findings demonstrate that the PaTS-Wheel achieved a superior obstacle-climbing ability (70% of wheel diameter vs. 25% for standard wheels), while maintaining remarkably consistent energy consumption across varied terrain types—only a 4% variation compared to 35.7% for standard wheels. The wheel exhibits predictable mechanical behaviour and balanced vibration characteristics, though with 39.8% higher baseline energy consumption than traditional wheels. However, practical limitations, including debris entrapment between flexure components and the need for adequate robot ground clearance, constrain real-world performance. The DogBone-Wheel’s modular construction offered manufacturing flexibility, but it reduced traction due to the use of PLA components. These results validate the potential of passive transformation mechanisms to enhance robotic mobility in challenging terrain with consistent energy performance and minimal active control. Repo with print files, data and processing code: https://github.com/robert-stevenson-1/DogBone-Wheels .