To set this up, after a User selects a car, motorcycle, or gas station in the registration process, the workflow would also need to save that icon image file, as the value for the Icon image field (type: image, list: no). It would be best to have these images be .svg. Here is an example of the data structure (if the Users were registering a Place)
In the above property editor, I selected that the Icon is data dependent. This tell Bubble to dynamically display the icon marker which is associated with that Place.
If any of this was confusing, feel free to share a link to your app in the editor and I can definitely assist with setting this up.