Here's a good article about how some new developments in the UK are planning on bulding new towns with 15 mph speed limit. The objective is to get people out of cars and promote cycling and public transportation. Actually, it's being created to cut back emissions for global warming.
Regardless, I would love to live in a town where ALL the streets had a 15 mph speed limit. I'm sick of the 25 mph speed limit because the motorist know they can travel up to 37 mph without any fear of getting a speeding ticket. I don't consider it a global waming issue at all but a quality of life issue.
I suspect that a 15 mph speed limit will mean the cars will finally travel at 25
Don't forget to read the pro-motoring comments below the article.