I believe I commented on this in another thread way back, but here goes. With dark tinted windows, decals won't work for me, though I'm grateful for them as the nose prints and dog drool don't show from the outside
Conscious of cost, a few years ago I bought magnets from VistaPrint. They were OK but very flimsy, falling off at speed and within a year fading and bubbling in the sun.
Last Fall I designed and bought new ones locally and they're terrific ... even stay on going through the carwash. They cost me around $300 but so worth it. I'm meeting with a new client tomorrow. I doubt he found me on the Internet as I've just designed a new website in Wordpress and have yet to promote it. Perhaps he saw the "Wizmobile" around town? I'll find out tomorrow.
You can check out my magnets on the gallery in my website
http://wordprowizard.com/gallery.
Lynne