I just got an 05 Cayenne S. Is it possible to start off in D1 without turning off the PSM???

 

yes Mine will
I put it in tiptronic mode

 

Is that the only way?

 

the computer will start you off in the best gear it chooses for the temperture and conditions it reads. Mine will start in D1 if it is cold out, but mostly in D2. Why do you want it to start in D1 over D2? It also tries to get the best gas mileage, therefore skipping first gear. (so they say)