Welcome, kanne,
Since you're new here to this site, you may not be aware of the differences between the 3 model years of the current body style. There was virtually no difference between the '04 & '05 except for the addition of the rear wiper as standard equipment thus reducing the number of option pkg's from 9 in '04 to 6 in '05.
So all '05's have the rear wiper [this may not be completely true depend'g on if the wiper was also included on the NO-option pkg not available to the general public (only to rental companies, municipal fleets, & taxi fleets---yes, I recently saw a New York City Prius in the yukky "taxi-yellow" paint job)], but naturally all rear wiper-equiped Priuses are not '05's.
There are many mostly subtle changes for '06, both inside & out. I own an '05 & even though I may consider them subtle, many of the '04 & '05 owners consider the changes major & eagerly & warmly welcomed. Besides the color changes, the most obvious ones easily visible from the side on the outside are: #1 the yellow/orange side reflectors now in BOTH the top & bottom half of the headlight assembly (instead of just in the top), & #2 the addition of chrome "HYBRID" script blending into the "hybrid synergy drive" emblem (as seen on the rear of the cars) placed on both sides of the '06 between the rear of the front wheel wells & the front edge of the front doors.
All that said, if the grays you are seeing have the HYBRID script/emblem blend on the side (as desribed above), then they are the new '06 "Magnetic Gray". If they don't have the script/emblem blend on the side, then they are the '04/'05 "Tideland Pearl Metallic" color, which I think is a dark (charcoal?) gray. Some people say the "Tideland" is a greenish gray, but I've viewed that color on a stationary car in varying degrees of daylight from all different angles on all 4 sides & have not yet seen a hint of green in it.
Even though I've been long-winded, I hope this has helped to answer your question. Have you ordered one yet? It pays to shop around for the best price (never pay more than MSRP---it may even be possible to get lower, as some have). Also when look'g for the right dealer, find one that gets a high quantity in his bi-monthly allotments & is willing to work with you to swap with another dealer (on the computer) to get you exactly the option pkg & int./ext. color combination you want & to specify (before your car arrives at the port) which port installed options (wheel locks, bumper applique, floor/cargo mats, 1st aid kit, etc) you will or won't accept.
The 1st dealer I approached only got 2 or 3 cars/month & had such a long wait'g list that if I had ordred with them in Nov '04, they said I would get my car around Feb '07 (after the factory production rate was increased, that wait was cut from the 2 1/4 years to a little over one year). The next dealer got the same 2 or 3 /month but would close off their wait'g list at 25 [to guarantee a shorter wait by not over-signing for their delivery rate (to prevent like how the airlines purposely overbook their flights & you arrive ready to travel & you find out that not everybody WITH A RESERVATION will be able to get on board)], so I ordered with them. But that dealer refused to try to get me the colors & options I requested,so after 5 1/2 months & my refusing 3 fully-loaded '05 pkg 6's (not what I wanted or could afford) during that time, they told me "Take what we offer you or be moved to the bottom of our list again". So I got my deposit back & left them.
I found another dealer that also was only charg'g MSRP but that got 7 cars/month & had a shorter wait'g list (because he was deliver'g faster).He didn't even ask for a deposit & he promised me he would get me the EXACT car I wanted, no more, no less. In 6 weeks with him I got my EXACT car, so he got a nice tip. It was such a pleasure work'g with him (he knew the car inside & out, down to the last bolt & computer chip). So, you see, it does pay to shop around. You're not really as much of a captive customer as they (or you) think. This really got long-winded, but I hope it will help you as well. Good luck!
Ken (in Bolton,Ct)