I actually built a circuit yesterday, but I still need to tweak it some. I'll post a schematic once I have it working the way I want. It can be built out of parts available at Radio Shack, but being able to solder and work with electronic parts is necessary.

I also found a fuse on my A4 to tap in to that cuts out when you crank the engine over. This is better than using a fuse that stays on when the starter is engaged.

With the combination of switching circuits and the delayed-on circuit, my V1 turns on a couple seconds after I start the engine.