If you want to make a mechanical or tripod-like contraption don't use the vehicle editor. Instead, use the creature editor and use the captain parts or other parts in order to cover
Spore Bot Parts | Peatix
Spore Patch 6 Dr. Pepper Bot Parts Pack 2018 | The Sporum The Spore Forum
Captain for my Robotic Earth-Inhabiting Species [Solar Empire] : r/Spore