I will not be as easy as this. In Blender, you need to use two Mode. One is the Object Mode. This is has the whole object selected, so you can move it around, rotate, scale, etc; It is the default when Blender starts or an Object is loaded in.
By pressing the TAB key, you enter the Edit mode. This is the mode you want to be in. To the left there are a series of boxes. When you move the mouse over them a label should appear under the mouse. Move the mouse over the 2nd to last button. This is the Edit button. Directly below this are a group of boxes. One has <Mat>. This moves between different Materials. Below this is select and deselect. Using the <Mat> button, click on the < > buttons to move back and forth between materials. You can use select to select the whole material vertex group. The color box will change as you move between Materials. Deselect will turn the material off again.
When the correct material is found, select it. Then go back up to the boxes and click on the shading button. You should see a sphere which shows the current material raytraced on the left. This is a preview of the color and properties of the material. There should be in the second group to the right, the color chooser section under Material. This is where you can change the color, spec color, and mirror colors. When you click on a color, a window opens with the color picker. You can use the sliders to select colors. If you move the mouse off this, the window closes. This is normal. Just keep the mouse in the window until you have the color/s you want. Then press the RETURN key.
Press the TAB key again. This puts you back into the Object Mode. The Car/object should have a pink line around it. If it does not, Right click on the object with the right mouse button. It is selected.
Goto the File Menu at the top and go down to Export. Select Wavefront from the sub menu. A save object window will appear. It will show the current output path next to the P. Name the object below this and click on Export Wavefront Object on the right. A new window will appear. You'll want to select (becomes dark) Rotate X90, Copy Images, Edges, Triangulate, Polygroups, Materials, UV, Nurbs, Normals, HQ, Objects, Groups, Material Groups, and Keep Vertex Order. Then Click Export. The object is saved and ready to load into Terragen 2.
In Terragen 2, load the object using the obj import. It will ask if the object is XFrog, select No. A really tiny object will appear at 0,0,0. Move the camera down so the object is centered. Rescale the object so you can comfortably move the camera around it. This changes the objects actual size in T2.
Go to the Shaders tab. It should say parts 01. Change this to Multishader. Goto the Multishader by opening it. Click on stay open. Each Material should have it own slot. So add default shaders to each slot one at a time. Give the color of the default shader an obnoxious bright green or pink. This lets you know what part of the model you are working with. Now you can change the colors, and the other things in the defaults shader's window. Do this until all the object is colored how you wish; all materials are changed as desired.
To save this for easy importing later, go to the object in the nodes. Right click and select Save As Terragen (tgo). This will save the object and the multishader elements so you don't have to do this again.
A note, the reflectivity in the default shader does not cause a mirror/reflection. I think it has to do with the light bounce back of the shader. A reflective shader must be input to the shader to make the surface 'mirror'.
That covers what I know about importing objects into Terragen 2 from Blender. There has to be more, but I have not discovered what yet.
Happy importing. Please abide by all International and National laws.
EDIT: I clicked on the show nodes button in the object. You can find all the materials here, just look at the top parts with the inputs. This is the default shader for each material.