Creating a 2D mimimap for a 3D car game

I am tring to create a minimap for my car game and while there are tonnes of tutorials for a top down camera map I want to actually show a 2d image and move that around based on the player location.
Exactly like this screenshot. Bottom left.
Can someone help me get a start on implementing this. I am really at a loss as the best way to do it.
I am thinking a top down camera with an image over my level just like the other tutorials all say to do but I feel a giant image over my game will increase loading and size when it can just be a very small jpeg that moves in the same way.
Anyway thanks for the help.

Check out Render Textures:

Create an isometric camera, make a simple script that moves the camera to the player x and z axis, create a render texture that uses that isometric camera, create a raw image, put the render texture in the texture slot. Boom.