A new supercharged 3.0-litre V6 petrol engine has been added to the Jaguar XJ line-up as part of a whole host of changes to the big executive saloon.

The 335bhp, 332lb ft unit replaces the normally aspirated 380bhp 5.0-litre V8 in the 2013 XJ range. Jaguar has confirmed the engine for the 2013 XF, and will appear in the new F-type sports car from launch.

A 3.0 V6-equipped XJ can crack 0-60mph in 5.7sec. Combined economy is rated at 30mpg, and CO2 emissions come in at 224g/km.

The engine will be mated to the familiar ZF eight-speed automatic gearbox as standard, which is the first time the transmission has been offered in the XJ. The XJ’s other engines – a 3.0-litre V6 turbodiesel and 5.0-litre supercharged V8 petrol – also now get the eight-speed auto as standard instead of the old six-speed gearbox.

All XJs also now get stop-start as standard, something which helps contribute to the improved 47mpg economy and 159g/km CO2 emissions of the oil-burning model.

Another addition as part of the XJ’s changes is the option of a new comfort suspension pack on all models. Some XJ traditionalists have criticised the current model for its hard edge, so the changes aim to increase ride isolation and boost passenger comfort.

DAB digital radio is now standard on all XJs, as is a new sound system.

The revised XJ goes on sale in September, priced from £56,260 for the entry-level diesel. The new V6 petrol engine-powered model starts at £65,365.