Why is my 2016 Mazda BT-50 3.2-litre using 14 litres per 100kms?

Unless you’ve changed the way you drive, a sudden jump in fuel economy suggests something wrong with either the mechanical or electronic side of things. Have the vehicle scanned and see if it throws any fault codes. From there, you can work out what component is giving you grief and target the problem accurately, rather than mess around for weeks flying blind.

One reason for the sharp increase in fuel consumption could be that the vehicle’s diesel particulate filter (DPF) is full and needs to be regenerated. If you’re not doing long, highway miles, the computer can take matters into its own hands and dump extra fuel into the exhaust system in an attempt to get the exhaust hot enough to regenerate the filter. But you could also be dealing with a faulty fuel-pressure regulator, worn injectors or even something as simple as a blocked air filter.