Tracking your fuel economy allows you to maintain an awareness of what works and what doesn't. It's also invaluable in identifying when your vehicle requires maintenance, for example if your economy drops dramatically with no change in driving conditions/style then it may be that your air filter needs replacing.
It's on this basis that the VehMan API was created, the Fuel Economy readouts on many vehicles are useful but only ever give a snapshot of a specific point in time. By recording the data properly, you can maintain a historic overview of how your vehicle performs at different times of the year, and whether there's been a gradual change in economy.
To keep track of the economy, simply make a note whenever you fill your tank, at a very basic level, you only need to record the following
- Litres purchased
- Tank filled?
- Mileage (main odometer reading)
It's usually helpful to record the Price per Litre, Garage and date as well though!