Iirc, according to "The Tipping Point", the company that makes kevlar does exactly what I suggested. Their method: They build a building and put 150 parking spaces out front. When people start parking on the grass, time to build a new building.
Funny, I had not thought of that (funny since I live without a car). Just repeating what I recalled from the book, not reccommending it as a method. :-)
