Picking up my new Prius this week...

Where to start...

Probably the biggest mod is to change the tires. If you're in Malibu CA, as your name might suggest, then the OEM tires may be fine, but in the wet northwest, they aren't good on wet or snowy roads. And they are really noisy.

The aerodynamic shape of the Prius seems to attract little rocks that can chip your paint. A 3M clear paint protective film can prevent this, without putting a big black bonnet on the front of your car. If you decide to do this, do it as soon as you can. I waited a few hundred miles and have a few chips.

Polish for the outside and protectant/anti-static for the inside. I like Zaino and 303 Protectant respectively.

With the XM you probably don't need an iPod/MP3 player adapter.

One little mod I did right away was put self-adhesive "brushed steel" plastic on the underside of the rigid piece of the cargo cover. You'll see what I mean when you get your car. It's just a plain white fabric that gets grubby with little handling.

Locking wheel lugs if you think your alloy rims might roll off some night.

You got the loaded package, so there's not a whole lot to add. Congratulations! I have a Silver Cloud too.

 

Just get the car and learn all it has to offer out of the box. Oh, and do some of the stuff Bill mentioned.