Jaguar has announced revisions to its XJ and XF engine line-up that cuts CO2 emissions and reduced benefit in kind tax liability.

The engine upgrades coincide with changes to the XJ for the 2013 model year, as well as prices and specifications for the new XF Sportbrake.

CO2 emissions for the XF are reduced to 135g/km for the 2.2D, which continues in 163bhp form in the entry-level version while the 190bhp variant has been boosted to 200bhp. Both engines have official fuel consumption of 55.4mpg on the combined cycle.

The 3.0-litre V6 diesel has undergone a 10g/km reduction and now has CO2 emissions of 159g/km, as well as lower fuel consumption. The lower ratings are the dame for both 240bhp and 275bhp twin-turbo variants.

The 5.0 V8 petrol variant has been replaced by a new 3.0-litre supercharged engine producing 340bhp, although the supercharged 5.0-litre V8 continues in the XFR.

The XF Sportbrake range will start at £31,940 on the road for the 2.2D SE Business (which includes standard satellite navigation and Bluetooth), with CO2 emissions from 135g/km.

Jaguar’s large saloon, the XJ also has CO2 emissions from 159g/km for the 275bhp 3.0D V6 with fuel consumption at 47.1mpg. The normally aspirated 5.0 V8 petrol variant has been replaced by a supercharged 3.0-litre V6. Other changes include a new premium audio system supplier and the addition of DAB as standard.