Funnily enough we are on hols on Wales at the moment, the 20 mph is in place in certain areas, some I understand, but there's one particular place that you have to go up a very steep hill, it's not possible to go up at 20mph, we're in hubby's car which has a bigger engine size than mine, he said I'd never make it up here in my car keeping to that speed, tbf some of the supposedly built up areas are still 30, and others 20 it's very confusing, I also don't sees how it's greener! The car in front of us the other day was struggling/ or not happy to keep to 20 and kept revving causing more pollution