Impressions are vehicles that you pass or that pass you, not hits to your website or rings on your telephone.
A vehicle wrap is big sheet of printed vinyl (up to 600 DPI) and then sprayed with a flexable clear coat. They last up to 4 years (manufacturers usually say longer but it's the abrasion that dulls them from washing and driving and not the sun or chemicals) and you can print any image on them that you want...or the DMV will let you get away with. The process is alot like inkjet, however, they use solvents to print on the vinyl, therefore it is called soljet (or Eco SolJet). When you are ready to sell the car, or want to change you slogan, all youhave to do is peal it off and reveal the perfect unfaded paint behind it.
Plus with a vehicle wrap you have a reason to deduct more off your taxes if it is a personal car.
http://www.vehiclewraps.ca/portfolio.htm here's a link to some photos.
There are even companies that PAY YOU to wrap your vehicle with their company. If it's a late model vehicle and live in a high traffic area, they will actually pay youmore than what a lease or load costs you.
Word of advice though......if you buy the print online, do as much of the artwork as possible and have a professional install it.