Want to save millions of tons of CO2 per year? Want to improve a car's mpg? Want to save the NHS £M's per year in medication prescriptions for high blood pressure? EASY. Just turn off all traffic lights on roundabouts on - or related to - Motorway Junctions. Too radical? Then turn them off except at peak times because they're redundant for most of the time, traffic would flow more freely (starting from rest or engine idling is wasteful of fuel). Most roundabouts have good sightlines, enabling good traffic flow at approach. We are adults and can judge when to enter a roundabout or not. We can do without them (West Sussex has VERY FEW and they seem to survive).