Best Fuel???
 

Good evening. I recently returned home from a deployment to the desert. While I was away my wife bought me a 2001 VW Passat Wagon, 4Motion, v6, 30 Valve, Automatic Transmission.

I have owned a TDI Jetta and a 1.8L Jetta, both manual transmissions. I am trying to figure out what is the best fuel to run for performance and longevity of the car?