Car manufacturers publish figures based on official WLTP fuel economy tests, but real life driving usually offers lower (sometimes significantly lower) fuel economy figures. For high mileage motorway drivers, like yourself, diesels are usually a better buy. Hybrid vehicles offer good fuel economy for mixed driving as they regenerate battery power at low speeds, like around town. You can check our Real MPG stats here for most models: www.honestjohn.co.uk/real-mpg/

Our understanding is that Extra High Phase means motorway-like driving at a max of 81mph. However, saying that, I'm not sure you'll have much luck with Hyundai as having missold you the vehicle - especially if you don't have a record (like an email) of an employee telling you explicitly that the car you bought would get 50mpg on the motorway. Although, it's worth a try. What you could also try is using more premium fuel - like Shell or BP rather than supermarket fuel. We get reports from some readers that this improves fuel economy.