While I am all for conserving energy, etc. The latest campaign I am not in support of. It recommends that you drive 5 miles less/week in order to cut your CO2 emissions. Sometimes the only time I use my car is to drive to Asda to do the weekly shop. A round trip of 6 miles. If I cut my car use by 5miles/week...it would take me 6 weeks to get to Asda and back. Plus my car is diesel, and pollutes more on start up. I don't use my car excessively so I won't be following this bit of advice. I do walk most places, and usually if I know I need to shop I will drive to work to use my time efficiently, as work is closer to the supermarket. The rest of the time I walk to the shop/market/etc, as I have two dogs that need the exercise, and when I don't walk, my ankle becomes stiff and painful.
It might be more useful to encourage people to "downsize" their lifestyle. After all, expensive holidays abroad contribute more to CO2 emissions.