MG Motor has improved the CO2 emission figures from 139g/km to just 129g/km for the MG6 GT and Magnette Diesel variants.
This decrease in emissions drops the BIK band to 20%, resulting in a monthly tax bill of £56.47 per month for a MG6 DTi-TECH GT S.
The decrease in emissions also lowers the VED band for all MG6 Diesels from group E to a group D.
Despite improved emissions and fuel consumption, there is no change to the performance of the MG6 DTi-TECH, which still delivers a 150PS, 350NM diesel engine linked to a six-speed manual gearbox, a combination that provides a 0-60mph time of 8.9s.
There are also free upgrades on all diesel specifications until December 31.
Launched in 2012, the MG6 GT DTi-TECH starts at £16,995.
Under the current offers customers automatically upgrade from an S variant to an SE, benefiting from a saving of £1,200 and receiving additional equipment such as satellite navigation, rear parking sensors, cruise control and leather steering wheel.
Building on the SE trim, the TSE now offers a saving of £2,000 and features front parking sensors, 18" alloy wheels, rear parking camera, leather trim, Bluetooth, automatic headlights, automatic windscreen wipers and electric heated seats.
Magnette customers will be offered the opportunity to upgrade to an MG6 GT SE, saving £3,000.