It's believed that the long-standing 2.2-litre diesel unit would need redesigning in order to meet ever-toughening emissions legislation. The investment required to do would not be met with sales volumes significant enough to justify it.
The diesel 6 will still be available to order from stock until the end of the year, however, a UK spokesman has confirmed.
A number of makers have, in recent years, slimmed down or entirely axed their diesel offerings for models where the fuel was previously a popular choice. This is particularly true in the business and fleet markets, where company car users are now strongly incentivised to choose plug-in hybrids or EVs rather than oil-burners.
Mazda still offers the 2.2-litre diesel in the CX-5 SUV, and it's unclear if that will soon face the axe too. It's now the only diesel offering in Mazda's nine-strong range of UK bodystyles, as the volume-selling 3 was introduced in 2019 with the SkyActiv X spark controlled compression ignition petrol engine claimed to offer the economy of a diesel with the driver appeal of a petrol.