Examples in this video are a full circle, a corner with the rotation constrained to one quadrant, a particle and a static mesh (one faces camera, one turns with the car), and finally I got decals/spotlight projection working!
Here's the material and kismet for the corner element. The Sine and Cosine have their frequencies set to the max speed of the car x4. This is to constrain the rotation of the needle to one quadrant without any extra math in kismet.
The projected versions both have problems, as can be seen in this screenshot. Decals have clipping issues depending on how angled the surface is. Spotlights project perfectly but don't show up well, especially in lit areas. Clipping due to a material change, this was fixed when I went back to a quadruple blended vertex paint. Decals work fine.
Wiesmann GT MF5 speedometer research
I think I'll use that digital display for the boost indicator.
