Fuel consumption can vary for a variety of reasons, including driving style, the type of journey, vehicle load, tyre pressures, weather conditions and the condition of the vehicle. While the sudden drop in fuel consumption from 65mpg to 38mpg seems quite significant, the fact is that 380 miles with mostly town driving while achieving 48.4mpg is still a good figure. The official fuel consumption figure of 62.8mpg will include a good proportion of steady driving at out-of-town speeds, which is where most cars deliver their best performance.

Assuming the car is generally in good condition, is up to date with servicing requirements and the tyre pressures are correct, we would suggest resetting the trip computer and going for a drive on a dual carriageway or motorway at a steady 60-70mph. If it is showing average fuel consumption of high 50s or above, that would suggest the car is working as it should.