Not only can you be environmentally conscious by renting rather than putting another car on the road, you can be even more environmentally conscious by renting a car that gets ~45 mpg -- depending, of course, on how lead-footed you drive :o).
Unlike almost every Prius you'll find, this one has a sunroof, so you can better enjoy that same environment.
I have a device in my car that allows me to lock and unlock it remotely. Consequently, people are able to rent at odd hours (like when I'm at work - not when I'm asleep) because we don't need to meet in person.
In addition to a premium stereo and six-CD changer, there's a headphone-to-cassette adapter in the compartment just below the cassette player. (Yes, it's one of the last models to include both CDs and cassette.)
Lastly, I try to keep a sheet of Prius tips in the car for those who've never driven one before (or need a refresher). I say "try to" because people keep walking off with it. Please don't be one of those people. :o)
No smoking, please. Pets are OK only as long as they're in a carrier.