Was that reflective vinyl that you used too?
All in all, that's a very cool design, and as you said, the client got exactly what she wanted which is the key. What I really like about it is the phone number is VERY easy to read. All too often I'm driving down the highway, see a cool graphic advertising a company, and the phone number is the most difficult thing to make out in the whole design. Riiiiiiight. Also, I'm not sure how many times you've seen it, but I see it plenty around here, where although Connecticut has two area codes, and borders New York (as well as having many New York vehicles traveling through it all day every day), some insist on not having an area cods in the graphic. ...I like to guess at numbers when I'm trying to quickly jot down a company and number I happen to see while driving.
I also like how even though it's big enough for anyone to read, and is dead smack in the center of the windows, it's small enough to not impede the drivers view out any of the windows.
Did she already have that scissor logo, or did you make it for her?