What Euro 4 means for you
Euro 4 is the EU exhaust emissions standard that most petrol cars from 2006 meet. It matters most for London drivers: a petrol car that doesn't meet Euro 4 pays the ULEZ charge of £12.50 a day, every day except Christmas Day. Diesel cars need Euro 6 instead, and most from September 2015 meet it.
Before buying, check whether the car would be charged where you drive. Birmingham charges £8 a day and Bristol £9, and electric cars always comply. GetFreeCarCheck's free check shows ULEZ status, so you can confirm it before you commit.